### MASS LIMITS for Diquarks

<table><thead><tr><th>VALUE (GeV)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td colspan="5">&gt;7200 (CL = 95%) OUR LIMIT</td></tr><tr><td>none 600–7200</td><td>95</td><td>1 SIRUNYAN</td><td>18B0 CMS</td><td>E<sub>6</sub> diquark</td></tr><tr><td>none 600–6900</td><td>95</td><td>2 KHACHATRY...17W CMS</td><td></td><td>E<sub>6</sub> diquark</td></tr><tr><td>none 1500–6000</td><td>95</td><td>3 KHACHATRY...16K CMS</td><td></td><td>E<sub>6</sub> diquark</td></tr><tr><td>none 500–1600</td><td>95</td><td>4 KHACHATRY...16L CMS</td><td></td><td>E<sub>6</sub> diquark</td></tr><tr><td>none 1200–4700</td><td>95</td><td>5 KHACHATRY...15V CMS</td><td></td><td>E<sub>6</sub> diquark</td></tr><tr><td colspan="5">● ● ● We do not use the following data for averages, fits, limits, etc. ● ● ●</td></tr><tr><td>&gt;3750</td><td>95</td><td>6 CHATRCHYAN 13A CMS</td><td></td><td>E<sub>6</sub> diquark</td></tr><tr><td>none 1000–4280</td><td>95</td><td>7 CHATRCHYAN 13AS CMS</td><td></td><td>Superseded by KHACHATRYAN 15V</td></tr><tr><td>&gt;3520</td><td>95</td><td>8 CHATRCHYAN 11Y CMS</td><td></td><td>Superseded by CHATRCHYAN 13A</td></tr><tr><td>none 970–1080, 1450–1600</td><td>95</td><td>9 KHACHATRY...10 CMS</td><td></td><td>Superseded by CHATRCHYAN 13A</td></tr><tr><td>none 290–630</td><td>95</td><td>10 AALTONEN 09AC CDF</td><td></td><td>E<sub>6</sub> diquark</td></tr><tr><td>none 290–420</td><td>95</td><td>11 ABE</td><td>97G CDF</td><td>E<sub>6</sub> diquark</td></tr><tr><td>none 15–31.7</td><td>95</td><td>12 ABREU</td><td>940 DLPH</td><td>SUSY E<sub>6</sub> diquark</td></tr></tbody></table>

1. SIRUNYAN 18B0 search for resonances decaying to dijets in pp collisions at $\sqrt{s} = 13$ TeV.

2. KHACHATRYAN 17W search for resonances decaying to dijets in pp collisions at $\sqrt{s} = 13$ TeV.

3. KHACHATRYAN 16K search for resonances decaying to dijets in pp collisions at $\sqrt{s} = 13$ TeV.

4. KHACHATRYAN 16L search for resonances decaying to dijets in pp collisions at $\sqrt{s} = 8$ TeV with the data scouting technique, increasing the sensitivity to the low mass resonances.

5. KHACHATRYAN 15V search for resonances decaying to dijets in pp collisions at $\sqrt{s} = 8$ TeV.

6. CHATRCHYAN 13A search for new resonance decaying to dijets in pp collisions at $\sqrt{s} = 7$ TeV.

7. CHATRCHYAN 13AS search for new resonance decaying to dijets in pp collisions at $\sqrt{s} = 8$ TeV.

8. CHATRCHYAN 11Y search for new resonance decaying to dijets in pp collisions at $\sqrt{s} = 7$ TeV.

9. KHACHATRYAN 10 search for new resonance decaying to dijets in pp collisions at $\sqrt{s} = 7$ TeV.

10. AALTONEN 09AC search for new narrow resonance decaying to dijets.

11. ABE 97G search for new particle decaying to dijets.

12. ABREU 940 limit is from $e^+e^- \to \tau\bar{\tau}scs$. Range extends up to 43 GeV if diquarks are degenerate in mass.

### MASS LIMITS for g<sub>A</sub> (axigluon) and Other Color-Octet Gauge Bosons

Axigluons are massive color-octet gauge bosons in chiral color models and have axial-vector coupling to quarks with the same coupling strength as gluons.

<table><thead><tr><th>VALUE (GeV)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td colspan="5">&gt;6600 (CL = 95%) OUR LIMIT</td></tr><tr><td>none 1800–6600</td><td>95</td><td>1 SIRUNYAN</td><td>20AI CMS</td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>none 600–6100</td><td>95</td><td>2 SIRUNYAN</td><td>18B0 CMS</td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>none 600–5500</td><td>95</td><td>3 KHACHATRY...17W CMS</td><td></td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>none 1500–5100</td><td>95</td><td>4 KHACHATRY...16K CMS</td><td></td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>none 500–1000</td><td>95</td><td>5 KHACHATRY...16L CMS</td><td></td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>none 1300–3600</td><td>95</td><td>6 KHACHATRY...15V CMS</td><td></td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td colspan="5">● ● ● We do not use the following data for averages, fits, limits, etc. ● ● ●</td></tr><tr><td>&gt;2800</td><td>95</td><td>7 KHACHATRY...17Y CMS</td><td></td><td>pP → g<sub>A</sub>g<sub>A</sub> → 8j</td></tr><tr><td></td><td></td><td>8 AAD</td><td>16W ATLS</td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → b<span style="text-decoration: overline">b</span>b<span style="text-decoration: overline">b</span></td></tr><tr><td></td><td></td><td>9 KHACHATRY...16E CMS</td><td></td><td>pP → g<sub>A</sub>KK X, g<sub>A</sub>KK → t<span style="text-decoration: overline">t</span></td></tr><tr><td></td><td></td><td>10 KHACHATRY...15AV CMS</td><td></td><td>pP → Θ<sup>0</sup> Θ<sup>0</sup> → b<span style="text-decoration: overline">b</span>Zg</td></tr><tr><td></td><td></td><td>11 AALTONEN 13R CDF</td><td></td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → σσ, σ → 2j</td></tr><tr><td>&gt;3360</td><td>95</td><td>12 CHATRCHYAN 13A CMS</td><td></td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>none 1000–3270</td><td>95</td><td>13 CHATRCHYAN 13AS CMS</td><td></td><td>Superseded by KHACHATRYAN 15V</td></tr><tr><td>none 250–740</td><td>95</td><td>14 CHATRCHYAN 13AU CMS</td><td></td><td>pP → 2g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>&gt; 775</td><td>95</td><td>15 ABAZOV 12R D0</td><td></td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → t<span style="text-decoration: overline">t</span></td></tr><tr><td>&gt;2470</td><td>95</td><td>16 CHATRCHYAN 11Y CMS</td><td></td><td>Superseded by CHATRCHYAN 13A</td></tr><tr><td>none 1470–1520</td><td>95</td><td>17 AALTONEN 10L CDF</td><td></td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → t<span style="text-decoration: overline">t</span></td></tr><tr><td>none 260–1250</td><td>95</td><td>18 KHACHATRY...10 CMS</td><td></td><td>Superseded by CHATRCHYAN 13A</td></tr><tr><td>&gt; 910</td><td>95</td><td>19 AALTONEN 09AC CDF</td><td></td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>&gt; 365</td><td>95</td><td>20 CHOUDHURY 07 RVUE</td><td></td><td>pP → t<span style="text-decoration: overline">t</span>X</td></tr><tr><td></td><td></td><td>21 DONCHESKI 98 RVUE</td><td></td><td>Γ(Z → hadron)</td></tr><tr><td>none 200–980</td><td>95</td><td>22 ABE</td><td>97G CDF</td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>none 200–870</td><td>95</td><td>23 ABE</td><td>95N CDF</td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → q<span style="text-decoration: overline">q</span></td></tr><tr><td>none 240–640</td><td>95</td><td>24 ABE</td><td>93G CDF</td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>&gt; 50</td><td>95</td><td>25 CUYPERS 91 RVUE</td><td></td><td>σ(e<sup>+</sup>e<sup>-</sup> → hadrons)</td></tr><tr><td>none 120–210</td><td>95</td><td>26 ABE</td><td>90H CDF</td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>&gt; 29</td><td></td><td>27 ROBINETT 89 THEO</td><td></td><td>Partial-wave unitarity</td></tr><tr><td>none 150–310</td><td>95</td><td>28 ALBAJAR 88b UA1</td><td></td><td>pP → g<sub>A</sub>X, g<sub>A</sub> → 2j</td></tr><tr><td>&gt; 20</td><td></td><td>BERGSTROM 88 RVUE</td><td></td><td>pP → τX via g<sub>A</sub>g</td></tr><tr><td>&gt; 9</td><td></td><td>29 CUYPERS 88 RVUE</td><td></td><td>τ decay</td></tr><tr><td>&gt; 25</td><td></td><td>30 DONCHESKI 88b RVUE</td><td></td><td>τ decay</td></tr></tbody></table>

1. SIRUNYAN 20AI search for resonances decaying into dijets in pp collisions at $\sqrt{s} = 13$ TeV.

2. SIRUNYAN 18B0 search for resonances decaying to dijets in pp collisions at $\sqrt{s} = 13$ TeV.

3. KHACHATRYAN 17W search for resonances decaying to dijets in pp collisions at $\sqrt{s} = 13$ TeV.

4. KHACHATRYAN 16K search for resonances decaying to dijets in pp collisions at $\sqrt{s} = 13$ TeV.

5. KHACHATRYAN 16L search for resonances decaying to dijets in pp collisions at $\sqrt{s} = 8$ TeV with the data scouting technique, increasing the sensitivity to the low mass resonances.

6. KHACHATRYAN 15V search for resonances decaying to dijets in pp collisions at $\sqrt{s} = 8$ TeV.

7. KHACHATRYAN 17Y search for pair production of color-octet gauge boson g<sub>A</sub> each decaying to 4j in pp collisions at $\sqrt{s} = 8$ TeV.

8. AAD 16W search for a new resonance decaying to a pair of b and B<sub>H</sub> in pp collisions at $\sqrt{s} = 8$ TeV. The vector-like quark B<sub>H</sub> is assumed to decay to bH. See their Fig. 3 and Fig. 4 for limits on σ · B.

9. KHACHATRYAN 16E search for KK gluon decaying to t<span style="text-decoration: overline">t</span> in pp collisions at $\sqrt{s} = 8$ TeV.

10. KHACHATRYAN 15AV search for pair productions of neutral color-octet weak-triplet scalar particles (Θ<sup>0</sup>), decaying to b<span style="text-decoration: overline">b</span>, Zg or γg, in pp collisions at $\sqrt{s} = 8$ TeV. The Θ<sup>0</sup> particle is often predicted in coloron (G', color-octet gauge boson) models and appear in the pp collisions through G' → Θ<sup>0</sup> Θ<sup>0</sup> decays. Assuming B(Θ<sup>0</sup> → b<span style="text-decoration: overline">b</span>) = 0.5, they give limits m<sub>Θ0</sub> > 623 GeV (426 GeV) for m<sub>G'</sub> = 2.3 m<sub>Θ0</sub> (m<sub>G'</sub> = 5 m<sub>Θ0</sub>).

11. AALTONEN 13R search for new resonance decaying to σσ, with hypothetical strongly interacting σ particle subsequently decaying to 2 jets, in p<span style="text-decoration: overline">p</span> collisions at $\sqrt{s} = 1.96$ TeV, using data corresponding to an integrated luminosity of 6.6 fb<sup>-1</sup>. For 50 GeV < m<sub>σ</sub> < m<sub>g<sub>A</sub></sub>/2, axigluons in mass range 150–400 GeV are excluded.

12. CHATRCHYAN 13A search for new resonance decaying to dijets in pp collisions at $\sqrt{s} = 7$ TeV.

13. CHATRCHYAN 13AS search for new resonance decaying to dijets in pp collisions at $\sqrt{s} = 8$ TeV.

14. CHATRCHYAN 13AU search for the pair produced color-octet vector bosons decaying to q<span style="text-decoration: overline">t</span> pairs in pp collisions. The quoted limit is for B(g<sub>A</sub> → q<span style="text-decoration: overline">t</span>) = 1.

15. ABAZOV 12R search for massive color octet vector particle decaying to t<span style="text-decoration: overline">t</span>. The quoted limit assumes g<sub>A</sub> couplings with light quarks are suppressed by 0.2.

16. CHATRCHYAN 11Y search for new resonance decaying to dijets in pp collisions at $\sqrt{s} = 7$ TeV.

17. AALTONEN 10L search for massive color octet non-chiral vector particle decaying into t<span style="text-decoration: overline">t</span> pair with mass in the range 400 GeV < M < 800 GeV. See their Fig. 6 for limit in the mass-coupling plane.

18. KHACHATRYAN 10 search for new resonance decaying to dijets in pp collisions at $\sqrt{s} = 7$ TeV.

19. AALTONEN 09AC search for new narrow resonance decaying to dijets.

20. CHOUDHURY 07 limit is from the t<span style="text-decoration: overline">t</span> production cross section measured at CDF.

21. DONCHESKI 98 compare α<sub>S</sub> derived from low-energy data and that from Γ(Z → hadrons)/Γ(Z → leptons).

22. ABE 97G search for new particle decaying to dijets.

23. ABE 95N assume axigluons decaying to quarks in the Standard Model only.

24. ABE 93G assume Γ(g<sub>A</sub>) = Nα<sub>S</sub>m<sub>g<sub>A</sub></sub>/6 with N = 10.

25. CUYPERS 91 compare α<sub>S</sub> measured in T decay and that from R at PEP/PETRA energies.

26. ABE 90H assumes Γ(g<sub>A</sub>) = Nα<sub>S</sub>m<sub>g<sub>A</sub></sub>/6 with N = 5 (Γ(g<sub>A</sub>) = 0.09m<sub>g<sub>A</sub></sub>). For N = 10, the excluded region is reduced to 120–150 GeV.

27. ROBINETT 89 result demands partial-wave unitarity of J = 0 t<span style="text-decoration: overline">t</span> → t<span style="text-decoration: overline">t</span> scattering amplitude and derives a limit m<sub>g<sub>A</sub></sub> > 0.5 m<sub>t</sub>. Assumes m<sub>t</sub> > 56 GeV.

28. ALBAJAR 88 result is from the nonobstruction of a peak in two-jet invariant mass distribution. Γ(g<sub>A</sub>) < 0.4 m<sub>g<sub>A</sub></sub> assumed. See also BAGGER 88.

29. CUYPERS 88 requires Γ(T → g<sub>A</sub>g<sub>A</sub>) < Γ(T → g<span style="text-decoration: overline">g</span>g). A similar result is obtained by DONCHESKI 88.

30. DONCHESKI 88b requires Γ(T → g<span style="text-decoration: overline">q</span><span style="text-decoration: overline">q</span>) / Γ(T → g<span style="text-decoration: overline">g</span>g) < 0.25, where the former decay proceeds via axigluon exchange. A more conservative estimate of < 0.5 leads to m<sub>g<sub>A</sub></sub> > 21 GeV.

### MASS LIMITS for Color-Octet Scalar Bosons

<table><thead><tr><th>VALUE (GeV)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td colspan="5">● ● ● We do not use the following data for averages, fits, limits, etc. ● ● ●</td></tr><tr><td>none 1800–3700</td><td>95</td><td>1 SIRUNYAN</td><td>20AI CMS</td><td>pP → S<sub>g</sub>X, S<sub>g</sub> → gg</td></tr><tr><td>none 600–3400</td><td>95</td><td>2 SIRUNYAN</td><td>18B0 CMS</td><td>pP → S<sub>g</sub>X, S<sub>g</sub> → gg</td></tr><tr><td></td><td></td><td>3 KHACHATRY...15AV CMS</td><td></td><td>pP → Θ<sup>0</sup> Θ<sup>0</sup> → b<span style="text-decoration: overline">b</span>Zg</td></tr><tr><td>none 150–287</td><td>95</td><td>4 AAD</td><td>13K ATLS</td><td>pP → S<sub>g</sub>S<sub>g</sub>X, S<sub>g</sub> → 2 jets</td></tr><tr><td colspan="5">1 SIRUNYAN 20AI search for resonances decaying into dijets in pp collisions at $\sqrt{s} = 13$ TeV. The limit above assumes S<sub>gg</sub> coupling k<sup>2</sup> = 1/2.</td></tr><tr><td colspan="5">2 SIRUNYAN 18B0 search for color octet scalar boson produced through gluon fusion process in pp collisions at $\sqrt{s} = 13$ TeV. The limit above assumes S<sub>gg</sub> coupling k<sup>2</sup> = 1/2.</td></tr><tr><td colspan="5">3 KHACHATRYAN 15AV search for pair productions of neutral color-octet weak-triplet scalar particles (Θ<sup>0</sup>), decaying to b<span style="text-decoration: overline">b</span>, Zg or γg, in pp collisions at $\sqrt{s} = 8$ TeV. The Θ<sup>0</sup> particle is often predicted in coloron (G', color-octet gauge boson) models and appear in the pp collisions through G' → Θ<sup>0</sup> Θ<sup>0</sup> decays. Assuming B(Θ<sup>0</sup> → b<span style="text-decoration: overline">b</span>) = 0.5, they give limits m<sub>Θ0</sub> > 623 GeV (426 GeV) for m<sub>G'</sub> = 2.3 m<sub>Θ0</sub> (m<sub>G'</sub> = 5 m<sub>Θ0</sub>).</td></tr><tr><td colspan="5">4 AAD 13K search for pair production of color-octet scalar particles in pp collisions at $\sqrt{s} = 7$ TeV. Cross section limits are interpreted as mass limits on scalar partners of a Dirac gluino.</td></tr><tr><td colspan="5">● ● ● We do not use the following data for averages, fits, limits, etc. ● ● ●</td></tr><tr><td>VALUE</td><td>CL%</td><td>DOCUMENT ID</td><td>TECN</td><td>COMMENT</td></tr><tr><td>1 RAINBOLT</td><td>19</td><td>RVUE</td><td>χ<sup>0</sup> → ℓ<sup>+</sup>ℓ<sup>-</sup></td><td></td></tr><tr><td>2 SIRUNYAN</td><td>19AZ</td><td>CMS</td><td>χ<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup></td><td></td></tr></tbody></table>

### X<sup>0</sup> (Heavy Boson) Searches in Z Decays

Searches for radiative transition of Z to a lighter spin-0 state X<sup>0</sup> decaying to hadrons, a lepton pair, a photon pair, or invisible particles as shown in the comments. The limits are for the product of branching ratios.
<table><tr><td></td><td></td><td></td><td></td><td></td></tr><tr><td>3 BARATE</td><td>98U</td><td>Alep</td><td>X<sup>0</sup> → ℓℓ, q<span style="text-decoration: overline">q</span>, gg, γγ, νν</td><td></td></tr><tr><td>4 ACCIARRI</td><td>97Q</td><td>L3</td><td>X<sup>0</sup> → invisible particle(s)</td><td></td></tr><tr><td>5 ACTON</td><td>93E</td><td>OPAL</td><td>X<sup>0</sup> → γγ</td><td></td></tr><tr><td>6 ABREU</td><td>92D</td><td>DLPH</td><td>X<sup>0</sup> → hadrons</td><td></td></tr><tr><td>7 ADRIANI</td><td>92F</td><td>L3</td><td>X<sup>0</sup> → hadrons</td><td></td></tr><tr><td>8 ACTON</td><td>91</td><td>OPAL</td><td>X<sup>0</sup> → anything</td><td></td></tr><tr><td>&lt;1.1 × 10<sup>-4</sup></td><td>95</td><td>9 ACTON</td><td>X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup></td><td></td></tr><tr><td>&lt;9 × 10<sup>-5</sup></td><td>95</td><td>9 ACTON</td><td>X<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup></td><td></td></tr><tr><td>&lt;1.1 × 10<sup>-4</sup></td><td>95</td><td>9 ACTON</td><td>X<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup></td><td></td></tr><tr><td>&lt;2.8 × 10<sup>-4</sup></td><td>95</td><td>10 ADEVA</td><td>X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup></td><td></td></tr><tr><td>&lt;2.3 × 10<sup>-4</sup></td><td>95</td><td>10 ADEVA</td><td>X<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup></td><td></td></tr><tr><td>&lt;4.7 × 10<sup>-4</sup></td><td>95</td><td>11 ADEVA</td><td>X<sup>0</sup> → hadrons</td><td></td></tr><tr><td>&lt;8 × 10<sup>-4</sup></td><td>95</td><td>12 AKRAWY</td><td>X<sup>0</sup> → hadrons</td><td></td></tr></table>

1. RAINBOLT 19 limits are from $B(Z \to \ell^+\ell^-\ell^+\ell^-)$. See their Figs. 5 and 6 for limits in mass-coupling plane.

2. SIRUNYAN 19AZ search for $pp \to Z \to X^0\mu^+\mu^- \to \mu^+\mu^-\mu^+\mu^-$ events in $pp$ collisions at $\sqrt{s} = 13$ TeV. See their Fig. 5 for limits on $\sigma(pp \to X^0\mu^+\mu^-) \cdot B(X^0 \to \mu^+\mu^-)$.

3. BARATE 98U obtain limits on $B(Z \to \gamma X^0) \cdot B(X^0 \to \ell\ell, q\bar{q}, gg, \gamma\gamma, \nu\bar{\nu})$. See their Fig. 17.

4. See Fig. 4 of ACCIARRI 97Q for the upper limit on $B(Z \to \gamma X^0; E_\gamma > E_{min})$ as a function of $E_{min}$.

5. ACTON 93E give $\sigma(e^+e^- \to X^0\gamma) \cdot B(X^0 \to \gamma\gamma) < 0.4$ pb (95%CL) for $m_{X^0}=60 \pm 2.5$ GeV. If the process occurs via $\gamma$-channel $\gamma$ exchange, the limit translates to $\Gamma(X^0) \cdot B(X^0 \to \gamma\gamma)^2 < 20$ MeV for $m_{X^0} = 60 \pm 1$ GeV.

6. ABREU 92D give $\sigma_Z \cdot B(Z \to \gamma X^0) \cdot B(X^0 \to hadrons) < (3-10)$ pb for $m_{X^0} = 10-78$ GeV. A very similar limit is obtained for spin-1 $X^0$.

7. ADRIANI 92F search for isolated $\gamma$ in hadronic $Z$ decays. The limit $\sigma_Z \cdot B(Z \to \gamma X^0) \cdot B(X^0 \to hadrons) < (2-10)$ pb (95%CL) is given for $m_{X^0} = 25-85$ GeV.

8. ACTON 91 searches for $Z \to Z^*X^0, Z^* \to e^+e^-, \mu^+\mu^-, \text{ or } \nu\bar{\nu}$. Excludes any new scalar $X^0$ with $m_{X^0} < 9.5$ MeV/c if it has the same coupling to $ZZ^*$ as the MSM Higgs boson.

9. ACTON 91B limits are for $m_{X^0} = 60-85$ GeV.

10. ADEVA 91D limits are for $m_{X^0} = 30-89$ GeV.

11. ADEVA 91D limits are for $m_{X^0} = 30-86$ GeV.

12. AKRAWY 90J give $\Gamma(Z \to \gamma X^0) \cdot B(X^0 \to hadrons) < 1.9$ MeV (95%CL) for $m_{X^0} = 32-80$ GeV. We divide by $\Gamma(Z) = 2.5$ GeV to get product of branching ratios. For nonresonant transitions, the limit is $B(Z \to \gamma q\bar{q}) < 8.2$ MeV assuming three-body phase space distribution.

### MASS LIMITS for a Heavy Neutral Boson Coupling to $e^+e^-$

<table><thead><tr><th>VALUE (GeV)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead></table>

• • • We do not use the following data for averages, fits, limits, etc. • • •

<table><tr><td>none 55-61</td><td>1</td><td>ODAKA</td><td>89</td><td>VNS</td><td>Γ(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td></td><td></td><td></td><td></td><td></td><td>B(X<sup>0</sup> → had.) &gt; 0.2 MeV</td></tr><tr><td>&gt;45</td><td>95</td><td>2</td><td>DERRICK</td><td>86</td><td>HRS</td><td>Γ(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>) = 6 MeV</td></tr><tr><td>&gt;46.6</td><td>95</td><td>3</td><td>ADEVA</td><td>85</td><td>MRKJ</td><td>Γ(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>) = 10 keV</td></tr><tr><td>&gt;48</td><td>95</td><td>3</td><td>ADEVA</td><td>85</td><td>MRKJ</td><td>Γ(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>) = 4 MeV</td></tr><tr><td></td><td></td><td>4</td><td>BERGER</td><td>85B</td><td>PLUT</td><td></td></tr><tr><td>none 39.8-45.5</td><td>95</td><td>5</td><td>ADEVA</td><td>84</td><td>MRKJ</td><td>Γ(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>) = 10 keV</td></tr><tr><td>&gt;47.8</td><td>95</td><td>5</td><td>ADEVA</td><td>84</td><td>MRKJ</td><td>Γ(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>) = 4 MeV</td></tr><tr><td>none 39.8-45.2</td><td>95</td><td>5</td><td>BEHREND</td><td>84C</td><td>CELL</td><td></td></tr><tr><td>&gt;47</td><td>95</td><td>5</td><td>BEHREND</td><td>84C</td><td>CELL</td><td>Γ(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>) = 4 MeV</td></tr></table>

1. ODAKA 89 looked for a narrow or wide scalar resonance in $e^+e^- \to$ hadrons at $E_{cm} = 55.0-60.8$ GeV.

2. DERRICK 86 found no deviation from the Standard Model Bhabha scattering at $E_{cm} = 29$ GeV and set limits on the possible scalar boson $e^+e^-$ coupling. See their figure 4 for excluded region in the $\Gamma(X^0 \to e^+e^-) \cdot m_{X^0}$ plane. Electronic chiral invariance requires a parity doublet of $X^0$, in which case the limit applies for $\Gamma(X^0 \to e^+e^-) = 3$ GeV.

3. ADEVA 85 first limit is from $2\gamma, \mu^+\mu^-$, hadrons assuming $X^0$ is a scalar. Second limit is from $e^+e^-$ channel. $E_{cm} = 40-47$ GeV. Supersedes ADEVA 84.

4. BERGER 85B looked for effect of spin-0 boson exchange in $e^+e^- \to e^+e^-$ and $\mu^+\mu^-$ at $E_{cm} = 34.7$ GeV. See Fig. 5 for excluded region in the $m_{X^0} - \Gamma(X^0)$ plane.

5. ADEVA 84 and BEHREND 84C have $E_{cm} = 39.8-45.5$ GeV. MARK-J searched $X^0$ in $e^+e^- \to$ hadrons, $2\gamma, \mu^+\mu^-$, $e^+e^-$ and CELLO in the same channels plus $\tau$ pair. No narrow or broad $X^0$ is found in the energy range. They also searched for the effect of $X^0$ with $m_X > E_{cm}$. The second limits are from Bhabha data and for spin-0 singlet. The same limits apply for $\Gamma(X^0 \to e^+e^-) = 2$ MeV if $X^0$ is a spin-0 doublet. The second limit of BEHREND 84C was read off from their figure 2. The original papers also list limits in other channels.

### Search for $X^0$ Resonance in $e^+e^-$ Collisions

The limit is for $\Gamma(X^0 \to e^+e^-) \cdot B(X^0 \to f)$, where $f$ is the specified final state. Spin 0 is assumed for $X^0$.

<table><thead><tr><th>VALUE (keV)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead></table>

• • • We do not use the following data for averages, fits, limits, etc. • • •

<table><tr><td>&lt;10<sup>3</sup></td><td>95</td><td>1</td><td>ABE</td><td>93C VNS</td><td>Γ(ee)</td></tr><tr><td>&lt;(0.4-10)</td><td>95</td><td>2</td><td>ABE</td><td>93C VNS</td><td>f = γγ</td></tr></table>

<table><tr><td>&lt;(0.3-5)</td><td>95</td><td>3,4</td><td>ABE</td><td>93D TOPZ</td><td>f = γγ</td></tr><tr><td>&lt;(2-12)</td><td>95</td><td>3,4</td><td>ABE</td><td>93D TOPZ</td><td>f = hadrons</td></tr><tr><td>&lt;(4-200)</td><td>95</td><td>4,5</td><td>ABE</td><td>93D TOPZ</td><td>f = ee</td></tr><tr><td>&lt;(0.1-6)</td><td>95</td><td>4,5</td><td>ABE</td><td>93D TOPZ</td><td>f = μμ</td></tr><tr><td>&lt;(0.5-8)</td><td>90</td><td>6</td><td>STERNER</td><td>93 AMY</td><td>f = γγ</td></tr></table>

1. Limit is for $\Gamma(X^0 \to e^+e^-) \cdot m_{X^0} = 56-63.5$ GeV for $\Gamma(X^0) = 0.5$ GeV.

2. Limit is for $m_{X^0} = 56-61.5$ GeV and is valid for $\Gamma(X^0) \ll 100$ MeV. See their Fig. 5 for limits for $\Gamma = 1, 2$ GeV.

3. Limit is for $m_{X^0} = 57.2-60$ GeV.

4. Limit is valid for $\Gamma(X^0) \ll 100$ MeV. See paper for limits for $\Gamma = 1$ GeV and those for $J = 2$ resonances.

5. Limit is for $m_{X^0} = 56.6-60$ GeV.

6. STERNER 93 limit is for $m_{X^0} = 57-59.6$ GeV and is valid for $\Gamma(X^0) < 100$ MeV. See their Fig. 2 for limits for $\Gamma = 1, 3$ GeV.

### Search for $X^0$ Resonance in ep Collisions

<table><thead><tr><th>VALUE</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead></table>

• • • We do not use the following data for averages, fits, limits, etc. • • •

1. CHEKANOV 02B ZEUS $X \to jj$

1. CHEKANOV 02B search for photoproduction of $X$ decaying into dijets in ep collisions. See their Fig. 5 for the limit on the photoproduction cross section.

### Search for $X^0$ Resonance in $e^+e^-$ to $X^0\gamma$

<table><thead><tr><th>VALUE (GeV)</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead></table>

• • • We do not use the following data for averages, fits, limits, etc. • • •

1. ABBIENDI 03D OPAL $X^0 \to \gamma\gamma$
2. ABREU 00Z DLPH $X^0$ decaying invisibly
3. ADAM 96C DLPH $X^0$ decaying invisibly

1. ABBIENDI 03D measure the $e^+e^- \to \gamma\gamma\gamma$ cross section at $\sqrt{s}=181-209$ GeV. The upper bound on the production cross section, $\sigma(e^+e^- \to X^0\gamma)$ times the branching ratio for $X^0 \to \gamma\gamma$, is less than 0.03 pb at 95%CL for $X^0$ masses between 20 and 180 GeV. See their Fig. 9b for the limits in the mass-cross section plane.

2. ABREU 00Z is from the single photon cross section at $\sqrt{s}=183, 189$ GeV. The production cross section upper limit is less than 0.3 pb for $X^0$ mass between 40 and 160 GeV. See their Fig. 4 for the limit in mass-cross section plane.

3. ADAM 96C is from the single photon production cross at $\sqrt{s}=130, 136$ GeV. The upper bound is less than 3 pb for $X^0$ masses between 60 and 130 GeV. See their Fig. 5 for the exact bound on the cross section $\sigma(e^+e^- \to \gamma X^0)$.

### Search for $X^0$ Resonance in $Z \to f\bar{f}X^0$

The limit is for $B(Z \to f\bar{f}X^0) \cdot B(X^0 \to f)$ where $f$ is a fermion and $F$ is the specified final state. Spin 0 is assumed for $X^0$.

<table><thead><tr><th>VALUE</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead></table>

• • • We do not use the following data for averages, fits, limits, etc. • • •

<table><tr><td>&lt;3.7 × 10<sup>-6</sup></td><td>95</td><td>1</td><td>ABREU</td><td>96T DLPH</td><td>f=e,μ,τ; F=γγ</td></tr><tr><td></td><td></td><td>2</td><td>ABREU</td><td>96T DLPH</td><td>f=ν; F=γγ</td></tr><tr><td></td><td></td><td>3</td><td>ABREU</td><td>96T DLPH</td><td>f=q; F=γγ</td></tr><tr><td>&lt;6.8 × 10<sup>-6</sup></td><td>95</td><td>2</td><td>ACTON</td><td>93E OPAL</td><td>f=e,μ,τ; F=γγ</td></tr><tr><td>&lt;5.5 × 10<sup>-6</sup></td><td>95</td><td>2</td><td>ACTON</td><td>93E OPAL</td><td>f=q; F=γγ</td></tr><tr><td>&lt;3.1 × 10<sup>-6</sup></td><td>95</td><td>2</td><td>ACTON</td><td>93E OPAL</td><td>f=ν; F=γγ</td></tr><tr><td>&lt;6.5 × 10<sup>-6</sup></td><td>95</td><td>2</td><td>ACTON</td><td>93E OPAL</td><td>f=e,μ; f=ℓℓ, q<span style="text-decoration: overline">q</span>, νν</td></tr><tr><td>&lt;7.1 × 10<sup>-6</sup></td><td>95</td><td>2</td><td>BUSKULIC</td><td>93F ALEP</td><td>f=e,μ; F=ℓℓ, q<span style="text-decoration: overline">q</span>, νν</td></tr><tr><td></td><td></td><td>4</td><td>ADRIANI</td><td>92F L3</td><td>f=q; F=γγ</td></tr></table>

1. ABREU 96T obtain limit as a function of $m_{X^0}$. See their Fig. 6.

2. Limit is for $m_{X^0}$ around 180 GeV.

3. ABREU 96T obtain limit as a function of $m_{X^0}$. See their Fig. 15.

4. ADRIANI 92F give $\sigma_Z \cdot B(Z \to q\bar{q}X^0) \cdot B(X^0 \to \gamma\gamma) < (0.75-1.5)$ pb (95%CL) for $m_{X^0} = 10-70$ GeV. The limit is 1 pb at 60 GeV.

### Search for $X^0$ Resonance in $W^0X^0$ final state

<table><thead><tr><th>VALUE (MeV)</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead></table>

• • • We do not use the following data for averages, fits, limits, etc. • • •

1. AALTONEN 13AA CDF $X^0 \to jj$
2. CHATRCHYAN 12BR CMS $X^0 \to jj$
3. ABAZOV 11I D0 $X^0 \to jj$
4. ABE 97W CDF $X^0 \to b\bar{b}$

1. AALTONEN 13AA search for $X^0$ production associated with $W$ (or $Z$) in $p\bar{p}$ collisions at $E_{cm} = 1.96$ TeV. The upper limit on the cross section $\sigma(p\bar{p} \to W^0X^0)$ is 2.2 pb for $M_{X^0} = 145$ GeV.

2. CHATRCHYAN 12BR search for $X^0$ production associated with $W$ in $p\bar{p}$ collisions at $E_{cm} = 7$ TeV. The upper limit on the cross section is 5.0 pb at 95% CL for $m_{X^0} = 150$ GeV.

3. ABAZOV 11I search for $X^0$ production associated with $W$ in $p\bar{p}$ collisions at $E_{cm} = 1.96$ TeV. The 95% CL upper limit on the cross section ranges from 2.57 to 1.28 pb for $X^0$ mass between 110 and 170 GeV.

4. ABE 97W search for $X^0$ production associated with $W$ in $p\bar{p}$ collisions at $E_{cm} = 1.8$ TeV. The 95%CL upper limit on the production cross section times the branching ratio
for $X^0 \to b\bar{b}$ ranges from 14 to 19 pb for $X^0$ mass between 70 and 120 GeV. See their Fig. 3 for upper limits of the production cross section as a function of $m_{X^0}$.

## Search for $X^0$ Resonance in Quarkonium Decays

Limits are for branching ratios to modes shown. Spin 1 is assumed for $X^0$.

**VALUE** **CL%** **DOCUMENT ID** **TECN** **COMMENT**

• • • We do not use the following data for averages, fits, limits, etc. • • •

<table><tr><td>&lt; 3 &times; 10<sup>-5</sup> &minus; 6 &times; 10<sup>-3</sup></td><td>90</td><td>1 BALEST</td><td>95</td><td>CLE2</td><td>&tau;(15) &rarr; X<sup>0</sup>&chi;&#773;<sup>0</sup>,<br>m<sub>X<sup>0</sup></sub> &lt; 3.9 GeV</td></tr></table>

¹ BALEST 95 three-body limit is for phase-space photon energy distribution and angular distribution same as for $T \to gg\gamma$.

## Search for $X^0$ Resonance in $H(125)$ Decays

Spin 1 is assumed for $X^0$. See neutral Higgs search listing for pseudoscalar $X^0$.

**VALUE** **DOCUMENT ID** **TECN** **COMMENT**

• • • We do not use the following data for averages, fits, limits, etc. • • •

<table><tr><td>1 AAD</td><td>22j</td><td>ATLS</td><td>$X^0 \to \ell^+ \ell^-$</td></tr><tr><td>2 AABOUD</td><td>18AP ATLS</td><td>$H(125) \to Z^0 X^0$</td></tr><tr><td>3 AABOUD</td><td>18AP ATLS</td><td>$H(125) \to X^0 X^0$</td></tr></table>

¹ AAD 22j search for $X^0$ production via $H(125) \to X^0 X^0 / Z^0 X^0 \to 4\ell$ in $pp$ collisions at $\sqrt{s} = 13$ TeV. $X^0 \to \ell^+ \ell^-$ decay is assumed. See their Fig. 13 and Fig. 17 for limits on $\sigma \cdot B$ in $H(125) \to X^0 X^0$ and $H(125) \to Z^0 X^0$ channels.

² AABOUD 18AP use $pp$ collision data at $\sqrt{s} = 13$ TeV. $X^0 \to \ell^+ \ell^-$ decay is assumed. See their Fig. 9 for limits on $\sigma_H(125) \cdot B(Z^0 X^0)$.

³ AABOUD 18AP use $pp$ collision data at $\sqrt{s} = 13$ TeV. $X^0 \to \ell^+ \ell^-$ decay is assumed. See their Fig. 10 for limits on $\sigma_H(125) \cdot B(X^0 X^0)$.

## REFERENCES FOR Searches for New Heavy Bosons ($W'$, $Z'$, leptoquarks, etc.)

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Tumasyan et al. (CMS Collab.)</td></tr><tr><td>TUMASYAN</td><td>22AE</td><td>JHEP 2208 063</td><td>A. Tumasyan et al. (CMS Collab.)</td></tr><tr><td>TUMASYAN</td><td>22AL</td><td>JHEP 2209 088</td><td>A. Tumasyan et al. (CMS Collab.)</td></tr><tr><td>TUMASYAN</td><td>22D</td><td>PR D206 136888</td><td>A. Tumasyan et al. (CMS Collab.)</td></tr><tr><td>TUMASYAN</td><td>22E</td><td>PR D105 032008</td><td>A. Tumasyan et al. (CMS Collab.)</td></tr><tr><td>TUMASYAN</td><td>22H</td><td>PR D105 112007</td><td>A. Tumasyan et al. (CMS Collab.)</td></tr><tr><td>TUMASYAN</td><td>22I</td><td>PR D106 012002</td><td>A. Tumasyan et al. (CMS Collab.)</td></tr><tr><td>TUMASYAN</td><td>22J</td><td>PR D106 012004</td><td>A. Tumasyan et al. (CMS Collab.)</td></tr><tr><td>TUMASYAN</td><td>22R</td><td>JHEP 2204 047</td><td>A. Tumasyan et al. (CMS Collab.)</td></tr><tr><td>TUMASYAN</td><td>22S</td><td>JHEP 2204 087</td><td>A. Tumasyan et al. (CMS Collab.)</td></tr><tr><td>AAD</td><td>21AG</td><td>EPJ C81 313</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>21AQ</td><td>JHEP 2107 005</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>21AW</td><td>PR D104 112005</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>21AZ</td><td>JHEP 2110 013</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>21BB</td><td>JHEP 2101 209</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>21D</td><td>PRL 126 121802</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>21K</td><td>JHEP 2102 226</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>21S</td><td>JHEP 2105 093</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>21T</td><td>JHEP 2106 179</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>BURAS</td><td>21T</td><td>JHEP 2106 068</td><td>A.J. Buras et al. (TUM, CERN, ZURI+)</td></tr><tr><td>CADEDU</td><td>21A</td><td>PR D106 0116</td><td>M. Cagadu et al. (CAGL, CAGL INFN+)</td></tr><tr><td>COLARESI</td><td>21A</td><td>PR D104 072003</td><td>J. Colaresi et al. (MRION, FNAL, PNL+)</td></tr><tr><td>CRIVELLIN</td><td>21A</td><td>PR D103 115023</td><td>A. Crivellin, D. Mueller, L. Schnell (CERN, ZURI+)</td></tr><tr><td>KRIBS</td><td>21J</td><td>PRL 126 011801</td><td>G.D. Kribis, D. McKeen, N. Raj (OREG, TRIU)</td></tr><tr><td>SIRUNYAN</td><td>21J</td><td>PL B819 136446</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>21K</td><td>JHEP 2106 0208</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>21X</td><td>EPJ C81 688</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>21Y</td><td>PL B820 136535</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>TUMASYAN</td><td>21D</td><td>JHEP 2111 153</td><td>A. Tumasyan et al. (CMS Collab.)</td></tr><tr><td>AAD</td><td>20AD</td><td>PRL 125 131801</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>20AF</td><td>PR D125 251802</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>20AJ</td><td>PR D102 112008</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>20AK</td><td>JHEP 2010 112</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>20AM</td><td>JHEP 2010 061</td><td>G. Aad et al. (ATLAS Collab.)</td></tr></table>

<table><tr><td>AAD</td><td>20AT</td><td>EPJ C80 1165</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>20S</td><td>EPJ C80 737</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>20T</td><td>JHEP 2003 145</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>20W</td><td>JHEP 2006 151</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>20AI</td><td>JHEP 2010 156</td><td>R. Aaij et al. (LHCb Collab.)</td></tr><tr><td>ADACHI</td><td>20</td><td>PRL 124 141801</td><td>I. Adachi et al. (BELLE II Collab.)</td></tr><tr><td>AEBISCHER</td><td>20</td><td>PRL C80 252</td><td>J. Aebischer et al. (TUM, LAPTH, UCSC)</td></tr><tr><td>DEPPISCH</td><td>20</td><td>JHEP 2021 186</td><td>F.F. Deppisch, K. Fridel, J. Harz (TUM, TUM)</td></tr><tr><td>SIRUNYAN</td><td>20A</td><td>EPJ C80 3</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>20AI</td><td>JHEP 2005 033</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>20AQ</td><td>PRL 124 131802</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>20B</td><td>JHEP 2005 15448</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>20Q</td><td>EPJ C80 237</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>AABOUD</td><td>19AJ</td><td>PL B795 56</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>19AS</td><td>PR D99 092004</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>19AX</td><td>JHEP C79 733</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>19B</td><td>JHEP 1901 016</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>19BB</td><td>PL B798 134942</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>19D</td><td>PL B788 316</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>19E</td><td>PL B788 347</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>19V</td><td>JHEP 1905 142</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>19X</td><td>JHEP 1906 144</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>19Y</td><td>JHEP 052013</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>19D</td><td>JHEP 1909 091</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>Also</td><td>JHEP 2006 042 (errat.)</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>19L</td><td>PL B796 68</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>ABRAMOWICZ</td><td>19</td><td>PR D99 092006</td><td>H. Abramowicz et al. (ATLAS Collab.)</td></tr><tr><td>LONG</td><td>19</td><td>NP B943 114629</td><td>H.N. Long et al. (VALE, SIEG)</td></tr><tr><td>MANDAL</td><td>19</td><td>JHEP 1912 089</td><td>R. Mandal, A. Pich (IITI)</td></tr><tr><td>PANDEY</td><td>19</td><td>JHEP 1911 046</td><td>S. Pandey, S. Karmakar, S. Rakshit (NWS)</td></tr><tr><td>RAINBOLT</td><td>19</td><td>PR D99 013004</td><td>J.L. Rainbolt, M. Schmitt (NWS)</td></tr><tr><td>SIRUNYAN</td><td>19AA</td><td>JHEP 1904 031</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19A</td><td>PL C79 208</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19B</td><td>JHEP C79 280</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19AY</td><td>PL B792 107</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19AZ</td><td>PL B792 345</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19BC</td><td>JHEP 795 76</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19BI</td><td>PR D99 032014</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19BJ</td><td>JHEP 1905 052002</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19CB</td><td>PR D100 112007</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19CD</td><td>PRL 123 231803</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19CP</td><td>PL B798 134952</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19D</td><td>PRL 122 081804</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19I</td><td>JHEP 1901 051</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19J</td><td>JHEP 1903 127</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>19Y</td><td>JHEP 1903 170</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>AABOUD</td><td>18AA</td><td>PR D98 032015</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18AB</td><td>PR D98 032016</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18AD</td><td>PL B779 24</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18AF</td><td>PL B701 327</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>Also</td><td>JHEP 1803 174 (errat.)</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18AK</td><td>JHEP 1803 042</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18AL</td><td>JHEP 1803 009</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18AP</td><td>JHEP 1806 166</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18B</td><td>EPJ C78 24</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18BG</td><td>PL B78 C78 401</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18BI</td><td>PL C78 565</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18CH</td><td>PL B787 68</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18CI</td><td>PR D99 052008</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18CM</td><td>PR D98 092008</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18F</td><td>PL B777 91</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18G</td><td>JHEP 1801 055</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18K</td><td>PRL 120 161802</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>18N</td><td>PRL 121 081801</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>Also</td><td>JHEP 089 147</td><td>R. Aaij et al. (LHCb Collab.)</td></tr><tr><td>BOBONIKOV</td><td>18</td><td>PR D98 050929</td><td>I.D. Bobonikov, P. Osland, A.A. Pankov (BERG+)</td></tr><tr><td>SIRUNYAN</td><td>18</td><td>PL B777 39</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18AT</td><td>JHEP 1804 073</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18AX</td><td>JHEP 1805 088</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18AZ</td><td>JHEP 1806 128</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18BB</td><td>JHEP 1806 120</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18BJ</td><td>JHEP 1807 115</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18BK</td><td>JHEP 1807 075</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18BO</td><td>JHEP 1808 130</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18C</td><td>JHEP 1808 148</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18CZ</td><td>JHEP C78 707</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18DJ</td><td>JHEP 1809 101</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18DR</td><td>JHEP 1811 161</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18EC</td><td>PRL 121 241802</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18ED</td><td>JHEP 1811 172</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18E</td><td>PL B701 097</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18I</td><td>PRL 120 201801</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18P</td><td>PR D97 02006</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>18U</td><td>PR D98 032005</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>ZHANG</td><td>18A</td><td>JHEP C78 695</td><td>J. Zhang, C.-X., Yue, C.-H. Li (LNUDA)</td></tr><tr><td>AABOUD</td><td>18AK</td><td>PR D99 052004</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>17AO</td><td>PL B774 494</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>17AT</td><td>JHEP 1710 182</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>17B</td><td>PL B765 32</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>KHACHATRY...</td><td>17AX</td><td>PL B773 563</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>KHACHATRY...</td><td>17H</td><td>JHEP 1703 048</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>KHACHATRY...</td><td>17J</td><td>JHEP 1703 077</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>KHACHATRY...</td><td>17T</td><td>JHEP B768 57</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>KHACHATRY...</td><td>17U</td><td>PL B768 137</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>KHACHATRY...</td><td>17W</td><td>PL B769 520</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>KHACHATRY...</td><td>17Y</td><td>PL B770 257</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>KHACHATRY...</td><td>17Z</td><td>PL B770 278</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>17A</td><td>JHEP 1703 162</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>17AK</td><td>PL B774 533</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>17AP</td><td>JHEP 1710 180</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>17H</td><td>JHEP 1707 121</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>17I</td><td>JHEP 1708 029</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>17Q</td><td>JHEP 1707 001</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>17R</td><td>EPJ C77 636</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>17R</td><td>PRL 119 111802</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>SIRUNYAN</td><td>17V</td><td>JHEP 1709 053</td><td>A.M. Sirunyan et al. (CMS Collab.)</td></tr><tr><td>AABOUD</td><td>16</td><td>JP B759 229</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>16AA</td><td>EPJ C76 585</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>16AE</td><td>JHEP 1609 173</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>16P</td><td>EPJ C76 541</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>16U</td><td>PL B761 372</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AABOUD</td><td>16V</td><td>PL B762 334</td><td>M. Aaboud et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>16G</td><td>EPJ C76 107</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>16L</td><td>EPJ C76 210</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>16R</td><td>PL B755 285</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>16S</td><td>PL B754 302</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>AAD</td><td>16V</td><td>PL B758 249</td><td>G. Aad et al. (ATLAS Collab.)</td></tr><tr><td>BARRANCO</td><td>16</td><td>JP G43 11504</td><td>J. Barranco et al. (U.K. Dey, S. Mohanty)</td></tr><tr><td>DEY</td><td>16F</td><td>JHEP 1604 187</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>KHACHATRY...</td><td>16AF</td><td>PR D93 032004</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr></table>
# Gauge & Higgs Boson Particle Listings

## New Heavy Bosons

<table><tbody><tr><td>KHACHATRY... 16AG</td><td>PR D93 032005</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>Also</td><td>PR D95 039906 (errat.)</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 16AO</td><td>JHEP 1602 122</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 16AP</td><td>JHEP 1602 145</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 16BD</td><td>EPJ C76 237</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 16BE</td><td>EPJ C76 317</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 16E</td><td>PR D93 012001</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 16K</td><td>PRL 116 071801</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 16L</td><td>PRL 117 031802</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 16O</td><td>PRL B755 196</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KUMAR</td><td>PR D94 014022</td><td>G. Kumar</td><td></td></tr><tr><td>AAD</td><td>15AM JHEP 1507 157</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15AO JHEP 1508 148</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15AT EPJ C75 79</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15AU EPJ C75 69</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15AV EPJ C75 165</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15AZ EPJ C75 209</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>Also</td><td>PR D93 070 170 (errat.)</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15BB EPJ C75 263</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15CD PR D92 092001</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15CP JHEP 1512 055</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15O PR 115 031801</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15V PR D91 052005</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>15V CP D91 052007</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AALTONEN</td><td>PRL 115 061801</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>BESSAA</td><td>15 EPJ C75 97</td><td>A. Bessaa, S. Davidson</td><td></td></tr><tr><td>KHACHATRY... 15AE</td><td>JHEP 1504 025</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 15AF</td><td>JHEP 1507 042</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 15AV</td><td>JHEP 1509 201</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 15F</td><td>PRL 874 83</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 15F</td><td>PRL 114 101801</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 15O</td><td>PRL B748 255</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 15V</td><td>PR D91 092005</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 15V</td><td>PR D91 092009</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>SAHOO</td><td>15A PR D91 094019</td><td>S. Sahoo, R. Mohanta</td><td></td></tr><tr><td>AAD</td><td>14AI JHEP 1409 037</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>14AT PRL B738 428</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>14S PRL B737 223</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>14V PRL D91 052005</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>KHACHATRY... 14</td><td>JHEP 1408 173</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 14A</td><td>JHEP 1408 174</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 14O</td><td>JHEP C74 3149</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 14T</td><td>PRL B739 229</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>MAHART</td><td>14 PR D91 052028</td><td>R. Burtinez, F. Ochoa</td><td></td></tr><tr><td>PRIEELS</td><td>14 PRL D90 112003</td><td>P. Priels et al.</td><td>(LOUV, ETH, PSI+)</td></tr><tr><td>AAD</td><td>13AE JHEP 1306 033</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>13AO PRL D87 112006</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>13AQ PR D88 012004</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>13D JHEP 1301 029</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>13E PRL D87 112016</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>13K EPJ C73 2263</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>13S PRL B719 242</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AALTONEN</td><td>13A PRL 110 121802</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>13AA PR D88 092004</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>13B PRL 111 031802</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13A JHEP 1301 013</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13AF PRL B720 63</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13AJ PRL B723 280</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13AP PR D87 072002</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13AQ PR D87 072005</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13AS PR D87 114015</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13AU PRL 110 141802</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13BM PRL 111 211804</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>Also</td><td>PRL 112 119903 (errat.)</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13E PRL B718 1229</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13M PRL 083 19801</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>13U JHEP 1302 036</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>SAKAKI</td><td>13 PR D88 094012</td><td>Y. Sakaki et al.</td><td></td></tr><tr><td>AAD</td><td>12AV PRL 109 081801</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>12BB PR D85 112012</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>12D PRL D87 1209 041</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>12CC JHEP 1211 138</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>12CK PR D86 091103</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>12CR EPJ C72 2241</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>12H PRL B709 158</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>Also</td><td>PR D88 055004 (errat.)</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>12K PRL B723 2083</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>12M EPJ C72 2056</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>12O EPJ C72 2151</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AALTONEN</td><td>12AR PR D86 112002</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>12N PRL 108 211805</td><td>G. Aad et al.</td><td>(CDF Collab.)</td></tr><tr><td>ABAZOV</td><td>12P JHEP 051 051101</td><td>V. Abazov et al.</td><td>(ZEUS Collab.)</td></tr><tr><td>ABRAMOWICZ</td><td>12A PR D86 012005</td><td>H. Abramowicz et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12A FPR 109 141801</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12AG PR D86 052013</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12AI JHEP 1208 110</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12AQ C71 029 029</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>Also</td><td>JHEP 1403 132 (errat.)</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12AR PRL B717 351</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12BG PRL 109 261802</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12BL PRL 1212 015</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12BA PRL 109 251801</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12BR PRL 109 251802</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12BR PRL 109 251803</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12M PRL B714 158</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>12P PRL B716 82</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KOSNIK</td><td>12 PR D86 055004</td><td>N. Kosnik</td><td>(LALO, STFN)</td></tr><tr><td>AAD</td><td>11D PR D83 112006</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>11E PR D87 1251801</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AAD</td><td>11Z PRL C71 1809</td><td>G. Aad et al.</td><td>(ATLAS Collab.)</td></tr><tr><td>AALTONEN</td><td>11AD PR D84 072003</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>11AE PR D84 072004</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>11C PR D83 031102</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>11D PRL 121 012801</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>AARON</td><td>11A PRL B701 20</td><td>F. D. Aaron et al.</td><td>(H1 Collab.)</td></tr><tr><td>AARON</td><td>11B PRL B704 388</td><td>F. D. Aaron et al.</td><td>(H1 Collab.)</td></tr><tr><td>AARON</td><td>11C PRL B705 52</td><td>F. D. Aaron et al.</td><td>(H1 Collab.)</td></tr><tr><td>ABAZOV</td><td>11A PRL B695 88</td><td>V.M. Abazov et al.</td><td>(D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>11H PRL 107 011801</td><td>V.M. Abazov et al.</td><td>(D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>11I PRL D87 020801</td><td>V. Abazov et al.</td><td>(D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>11L PRL B699 145</td><td>V.M. Abazov et al.</td><td>(D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>11V PRL D84 071104</td><td>V.M. Abazov et al.</td><td>(D0 Collab.)</td></tr><tr><td>BUENO</td><td>11 PR D84 032005</td><td>J.F. Bueno et al.</td><td>(TWIST Collab.)</td></tr><tr><td>Also</td><td>PR D85 039908 (errat.)</td><td>J.F. Bueno et al.</td><td>(TWIST Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>11N JHEP 110 201802</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>11O JHEP 1108 005</td><td>S. Chatrchyan et al.</td><td>(CMS Collab.)</td></tr><tr><td>CHATRCHYAN</td><td>11Y PRL B704 123</td><td>I. Dorsner et al.</td><td>(CMS Collab.)</td></tr><tr><td>DORSNER</td><td>11 JHEP 1111 002</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 11D</td><td>PRL 106 201802</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>KHACHATRY... 11E</td><td>PRL 106 201803</td><td>V. Khachatryan et al.</td><td>(CMS Collab.)</td></tr><tr><td>AALTONEN</td><td>10L PRL B691 183</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>10N PRL 104 241801</td><td>T. Aaltonen et al.</td><td>(CDF Collab.)</td></tr><tr><td>ABAZOV</td><td>10L PRL B693 95</td><td>V.M. Abazov et al.</td><td>(D0 Collab.)</td></tr></tbody></table>

<table><tbody><tr><td>DEL-AGUILA</td><td>10 JHEP 1009 033</td><td>F. del Aguila, J. de Blas, M. Perez-Victoria (GRAN)</td></tr><tr><td>KHACHATRY... 10</td><td>PRL 105 211801</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>Also</td><td>PRL 106 029902</td><td>V. Khachatryan et al. (CMS Collab.)</td></tr><tr><td>WAUTERS</td><td>10 PR C82 055502</td><td>F. Wauters et al. (REZ, TAMU)</td></tr><tr><td>AALTONEN</td><td>09AC PR D79 112002</td><td>T. Aaltonen et al. (CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>09T PRL 102 031801</td><td>T. Aaltonen et al. (CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>09V PRL 102 091805</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>09 PL B671 224</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>09AF PL B681 224</td><td>J. Erler et al. (CDF Collab.)</td></tr><tr><td>ERLER</td><td>09 JHEP 0908 017</td><td>T. Aaltonen et al. (CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>08D PR D77 051102</td><td>T. Aaltonen et al. (CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>08P PR D77 091105</td><td>T. Aaltonen et al. (CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>08Y PRL 100 231801</td><td>T. Aaltonen et al. (CDF Collab.)</td></tr><tr><td>AALTONEN</td><td>08Z PRL 101 071802</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>08AA PL B668 98</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>08AD PL B668 357</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>08AN PRL 101 241802</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>08C PRL 100 031804</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>MACDONALD</td><td>08 PR D78 032010</td><td>R.P. MacDonald et al. (TWIST Collab.)</td></tr><tr><td>ZHANG</td><td>08 NP B802 247</td><td>Y. Zhang et al. (PKGU, UMD)</td></tr><tr><td>AALTONEN</td><td>07H PRL 99 171802</td><td>T. Aaltonen et al. (CDF Collab.)</td></tr><tr><td>ABAZOV</td><td>07E PL B647 74</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>07J PRL 99 061801</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>AKTAS</td><td>07A EPJ C52 833</td><td>A. Aktas et al. (H1 Collab.)</td></tr><tr><td>CHOUDHURY</td><td>07 PL B657 69</td><td>D. Choudhury et al. (HERA ZEUS Collab.)</td></tr><tr><td>MELCONIAN</td><td>07 PL B649 370</td><td>D. Melkonian et al. (TRIUMF)</td></tr><tr><td>SCHAEEL</td><td>07A PL C49 411</td><td>S. Schaef et al. (ALEPH Collab.)</td></tr><tr><td>SCHIAFFAN</td><td>07C PR D99 11803</td><td>M. Schumacher et al. (HEID, ILLG, KARL+)</td></tr><tr><td>SMIRVON</td><td>07 MPL A22 2353</td><td>A.D. Smirnov et al. (HEID, ILLG, KARL+)</td></tr><tr><td>ABAZOV</td><td>06A PL B636 183</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>06L PL B640 230</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZALLAH</td><td>06C EPJ C45 589</td><td>J. Abdallah et al. (DELPHI Collab.)</td></tr><tr><td>ABULENCIA</td><td>06L PR D96 211801</td><td>A. Abulencia et al. (CDF Collab.)</td></tr><tr><td>ABULENCIA</td><td>06T PR D73 051102</td><td>A. Abulencia et al. (CDF Collab.)</td></tr><tr><td>ABAZOV</td><td>05H PR D71 071104</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABULENCIA</td><td>05A EPJ 95 252001</td><td>A. Abulencia et al. (CDF Collab.)</td></tr><tr><td>ACOSTA</td><td>05I PR D71 112001</td><td>D. Acosta et al. (CDF Collab.)</td></tr><tr><td>ACOSTA</td><td>05V PR D72 051107</td><td>D. Acosta et al. (CDF Collab.)</td></tr><tr><td>ACOSTA</td><td>05R EPJ 95 131801</td><td>D. Acosta et al. (CDF Collab.)</td></tr><tr><td>AKTAS</td><td>05B PL B629 9</td><td>A. Aktas et al. (H1 Collab.)</td></tr><tr><td>CHEKANOV</td><td>05 PL B610 212</td><td>S. Chekanov et al. (HERA ZEUS Collab.)</td></tr><tr><td>CHEKANOV</td><td>05A EPJ C44 463</td><td>S. Chekanov et al. (HERA ZEUS Collab.)</td></tr><tr><td>CHYBET</td><td>05A ASP 23 313</td><td>R.H. Cyb90 015202</td></tr><tr><td>ABAZOV</td><td>04A PRL 92 221801</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>04C PR D69 111101</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>CHEKANOV</td><td>03B PR D68 052004</td><td>S. Chekanov et al. (ZEUS Collab.)</td></tr><tr><td>ABAZOV</td><td>03C PR D88 191801</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABIENDI</td><td>02C PL B526 233</td><td>G. Abiendi et al. (OPAL Collab.)</td></tr><tr><td>AFFOLDER</td><td>02B PR 88 071806</td><td>G. Abiendi et al. (OPAL Collab.)</td></tr><tr><td>CHEKANOV</td><td>02 PR D65 092004</td><td>G. Abiendi et al. (OPAL Collab.)</td></tr><tr><td>CHEKANOV</td><td>02B PR D531 9</td><td>G. Abiendi et al. (OPAL Collab.)</td></tr><tr><td>MUECK</td><td>02P PR D55 085037</td><td>A. Mueck, A. Pilatissis, R. Rueckl</td></tr><tr><td>ABAZOV</td><td>01B PR 87 061802</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ABAZOV</td><td>01D PR D64 092004</td><td>V.M. Abazov et al. (D0 Collab.)</td></tr><tr><td>ADLOFF</td><td>01C PL B523 234</td><td>C. Adloff et al. (H1 Collab.)</td></tr><tr><td>AFFOLDER</td><td>01C PR 87 231803</td><td>T. Affolder et al. (CDF Collab.)</td></tr><tr><td>BREITWEG</td><td>01 PR D63 050202</td><td>J. Breitweg et al. (ZEUS Collab.)</td></tr><tr><td>CHEDING</td><td>01P PL B517 167</td><td>K. Cheung et al. (H1 Collab.)</td></tr><tr><td>THOMAS</td><td>01 NP A694 559</td><td>E. Thomas et al. (H1 Collab.)</td></tr><tr><td>ABIENDI</td><td>00M EPJ C13 15</td><td>G. Abiendi et al. (OPAL Collab.)</td></tr><tr><td>ABBOTT</td><td>00C PRL 84 2088</td><td>B. Abbott et al. (D0 Collab.)</td></tr><tr><td>ABEU</td><td>00 PR PRL 84 5716</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>ABEU</td><td>00S PL B495 45</td><td>P. Abreu et al. (DELPHI Collab.)</td></tr><tr><td>ABEU</td><td>00Z EPJ C17 53</td><td>P. Abreu et al. (DELPHI Collab.)</td></tr><tr><td>ACCIARRI</td><td>00P PL B489 81</td><td>M. Acciarri et al. (L3 Collab.)</td></tr><tr><td>ADLOFF</td><td>00P PL B479 358</td><td>C. Adloff et al. (H1 Collab.)</td></tr><tr><td>AFFOLDER</td><td>00K PRL 85 2056</td><td>T. Affolder et al. (CDF Collab.)</td></tr><tr><td>BARATE</td><td>00P EPJ C12 183</td><td>R. Barate et al. (ALEPH Collab.)</td></tr><tr><td>BARGER</td><td>00 PL B480 149</td><td>V. Barger, K. Cheung (ZEUS Collab.)</td></tr><tr><td>BREITWEG</td><td>00E EPJ C16 253</td><td>J. Breitweg et al. (H1 Collab.)</td></tr><tr><td>CHAY</td><td>00E PR D61 035002</td><td>C. Chay, K.Y. Lee, S. Nam</td></tr><tr><td>CHO</td><td>00 MPL A15 311</td><td>G. Cho</td></tr><tr><td>CORNET</td><td>00 PR D61 037701</td><td>F. Cornet, M. Relano, J. Rico</td></tr><tr><td>DILADOVO</td><td>00 PR D60 000 030</td><td>A. Delgado, A. Latorre, M. Quiros</td></tr><tr><td>ERLER</td><td>00 PR PRL 84 212</td><td>J. Erler, P. Langacker</td></tr><tr><td>GABRIELLI</td><td>00 PR D62 055009</td><td>E. Gabrielli</td></tr><tr><td>RIZZO</td><td>00 PR D61 016007</td><td>T.G. Rizzo, J.D. Wells</td></tr><tr><td>ROSNER</td><td>00 PR D61 016006</td><td>J.L. Rosner</td></tr><tr><td>ZARHACKI</td><td>00 EPJ C17 695</td><td>A. Zarnecki</td></tr><tr><td>ABIENDI</td><td>99 EPJ C6 1</td><td>G. Abiendi et al. (OPAL Collab.)</td></tr><tr><td>ABBOTT</td><td>99P PRL 83 2896</td><td>B. Abbott et al. (D0 Collab.)</td></tr><tr><td>ABREU</td><td>99G PL B446 62</td><td>P. Abreu et al. (DELPHI Collab.)</td></tr><tr><td>ACKESTERF</td><td>99D EPJ C8 3</td><td>K. Ackerman et al. (OPAL Collab.)</td></tr><tr><td>ADLOFF</td><td>99 EPJ C14 447</td><td>C. Adloff et al. (H1 Collab.)</td></tr><tr><td>Also</td><td>99E PRL 14 553 (errat.)</td><td>R. Casalbuoni et al. (H1 Collab.)</td></tr><tr><td>CASALBUONI</td><td>99P PL B460 135</td><td>M. Czakon, J. Gluza, M. Zralek</td></tr><tr><td>CZAKON</td><td>99 PL B458 355</td><td>J. Erler, P. Langacker</td></tr><tr><td>ERLER</td><td>99 PL B456 68</td><td>W. Marciano</td></tr><tr><td>MARCIANO</td><td>99 PR D60 093006</td><td>M. Masiwa, P. Pomarol</td></tr><tr><td>MASIP</td><td>99 PR D60 096005</td><td>P. Math, M. Yamaguchi</td></tr><tr><td>NATH</td><td>99 PR D60 116004</td><td>A. Strumia</td></tr><tr><td>STRUMIA</td><td>99 PL B466 107</td><td>A. Strumia</td></tr><tr><td>ABBOTT</td><td>98E PRL 80 2051</td><td>B. Abbott et al. (D0 Collab.)</td></tr><tr><td>ABBOTT</td><td>98J PRL 81 38</td><td>B. Abbott et al. (D0 Collab.)</td></tr><tr><td>ABE</td><td>98P PRL 81 606</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>ABE</td><td>98V PRL 81 5742</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>ACCIARRI</td><td>98J PL B433 163</td><td>M. Acciarri et al. (L3 Collab.)</td></tr><tr><td>ACKESTERF</td><td>98J C2 441</td><td>K. Ackerman et al. (OPAL Collab.)</td></tr><tr><td>BARATE</td><td>98U EPJ C4 571</td><td>R. Barate et al. (ALEPH Collab.)</td></tr><tr><td>BAREBOIM</td><td>98 PL C1 369</td><td>G. Barenboim</td></tr><tr><td>CHO</td><td>98 EPJ C5 152</td><td>G. Cho, K. Hagiwara, S. Matsumoto</td></tr><tr><td>CONRAD</td><td>98 RMP 70 1341</td><td>J.M. Conrad, M.H. Shaevitz, T. Bolton</td></tr><tr><td>DONCHESKI</td><td>98 PR D58 097702</td><td>M.A. Doncheski, R.W. Robinett</td></tr><tr><td>GROSS-PILCH...98</td><td>hep-ex/9810015</td><td>C. Grosso-Pilcher, G. Landsberg, M. Paterno</td></tr><tr><td>ABE</td><td>99F PRL 78 2906</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>ABE</td><td>99Z PR D55 5263</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>ABE</td><td>97S PRL 79 2192</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>ABE</td><td>97W PRL 79 3819</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>ABE</td><td>97X PRL 79 4327</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>ACCIARRI</td><td>97Z PL K412 201</td><td>M. Acciarri et al. (L3 Collab.)</td></tr><tr><td>ARIMA</td><td>97T PRL D55 19</td><td>T. Arima et al. (VENUS Collab.)</td></tr><tr><td>BAREBOIM</td><td>97 PR D55 4213</td><td>G. Barenboim et al. (VALE, IFIC)</td></tr><tr><td>DEANDREA</td><td>97 PL B409 277</td><td>A. Deandrea (MARS)</td></tr><tr><td>DERRICK</td><td>97 ZPHY C73 613</td><td>M. Derrick et al. (ZEUS Collab.)</td></tr></tbody></table>
<table><tbody><tr><td>GROSSMAN</td><td>97</td><td>PR D55 2768</td><td>Y. Grossman, Z. Ligeti, E. Nardi (REHO, CIT)</td></tr><tr><td>JADACH</td><td>97</td><td>PR B408 281</td><td>G. Jadach, B.F.L. Ward, Z. Was (CERN, INP+)</td></tr><tr><td>STAHL</td><td>97</td><td>ZPY C74 73</td><td>A. Stahl, H. Voss (BONN)</td></tr><tr><td>ABACHI</td><td>96C</td><td>PRL 76 3271</td><td>S. Abachi et al. (D0 Collab.)</td></tr><tr><td>ABREU</td><td>96T</td><td>ZPY C72 179</td><td>P. Abreu et al. (DELPHI Collab.)</td></tr><tr><td>ADAM</td><td>96C</td><td>PL B380 471</td><td>W. Adam et al. (DELPHI Collab.)</td></tr><tr><td>AID</td><td>96B</td><td>PL B369 173</td><td>S. Aid et al. (H1 Collab.)</td></tr><tr><td>ALLET</td><td>96</td><td>PL B383 139</td><td>M. Allet et al. (VILL, LEUV, LOUV, WISC)</td></tr><tr><td>ABACHI</td><td>95E</td><td>PL B358 405</td><td>S. Abachi et al. (D0 Collab.)</td></tr><tr><td>ABE</td><td>95N</td><td>PRL 74 3538</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>BALEST</td><td>95</td><td>PR D51 2053</td><td>R. Balest et al. (CLEO Collab.)</td></tr><tr><td>KUZNETSOV</td><td>95</td><td>PRL 75 794</td><td>I.A. Kuznetsov et al. (PNPI, KIAE, HARV+)</td></tr><tr><td>KUZNETSOV</td><td>95B</td><td>PAN 58 2113</td><td>A.V. Kuznetsov, N.V. Mikheev (YARO)</td></tr><tr><td colspan="4">Translated from YAF 58 2228.</td></tr><tr><td>MIZUKOSHI</td><td>95</td><td>NP B443 20</td><td>J.K. Mizukoshi, O.J.P. Eboff, M.I. Gonzalez-Garcia (REHO, CIT)</td></tr><tr><td>ABREU</td><td>94D</td><td>ZPY C54 183</td><td>G. Bhattacharyya, J. Ellis, K. Sridhar (DELPHI Collab.)</td></tr><tr><td>BHATTACH...</td><td>94</td><td>PL B336 100</td><td>G. Bhattacharyya, J. Ellis, K. Sridhar (CERN)</td></tr><tr><td>Also</td><td>94</td><td>PL B338 522 (errat.)</td><td>G. Bhattacharyya, J. Ellis, K. Sridhar (CERN)</td></tr><tr><td>BHATTACH...</td><td>94B</td><td>PL B338 522 (errat.)</td><td>G. Bhattacharyya, J. Ellis, K. Sridhar (CERN)</td></tr><tr><td>DAVIDSON</td><td>94B</td><td>ZPY C61 613</td><td>S. Davidson, D. Bailey, B.A. Campbell (CFPA+)</td></tr><tr><td>KUZNETSOV</td><td>94</td><td>PL B329 295</td><td>A.V. Kuznetsov, N.V. Mikheev (YARO)</td></tr><tr><td>KUZNETSOV</td><td>94B</td><td>JETPL 60 315</td><td>I.A. Kuznetsov et al. (PNPI, KIAE, HARV+)</td></tr><tr><td colspan="4">Translated from ZETFP 60 311.</td></tr><tr><td>LEURER</td><td>94</td><td>PR D50 536</td><td>M. Leurer (REHO)</td></tr><tr><td>LEURER</td><td>94B</td><td>PRL D49 333</td><td>M. Leurer (REHO)</td></tr><tr><td>Also</td><td>94</td><td>PRL 71 1324</td><td>M. Leurer (REHO)</td></tr><tr><td>MAHANTA</td><td>94</td><td>PL B377 128</td><td>U. Mahanta (MEHTA)</td></tr><tr><td>SEVERIJNS</td><td>94</td><td>PRL 73 611 (errat.)</td><td>N. Severijns et al. (LOUV, WISC, LEUV+)</td></tr><tr><td>VILAIN</td><td>94B</td><td>PL B332 465</td><td>P. Villain et al. (CHARM II Collab.)</td></tr><tr><td>ABE</td><td>93C</td><td>PL B302 119</td><td>K. Abe et al. (VENUS Collab.)</td></tr><tr><td>ABE</td><td>93D</td><td>PL B304 373</td><td>T. Abe et al. (TOPAZ Collab.)</td></tr><tr><td>ABE</td><td>93G</td><td>PL B71 2542</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>ABREU</td><td>93E</td><td>PRL B316 620</td><td>P. Abreu et al. (DELPHI Collab.)</td></tr><tr><td>ACTON</td><td>93E</td><td>PL B311 391</td><td>P.D. Acton et al. (OPAL Collab.)</td></tr><tr><td>ADRIAN</td><td>93M</td><td>PL B313 1</td><td>O. Adriani et al. (L3 Collab.)</td></tr><tr><td>ALITTI</td><td>93</td><td>NP B400 3</td><td>J. Alititi et al. (UA2 Collab.)</td></tr><tr><td>BHATTACH...</td><td>93</td><td>PRL D47 3693</td><td>G. Bhattacharyya et al. (CALC, JADA, ICTP+)</td></tr><tr><td>BUSKULIC</td><td>93F</td><td>PL B308 425</td><td>D. Buskulic et al. (ALEPH Collab.)</td></tr><tr><td>DERRICK</td><td>93</td><td>PL B306 173</td><td>M. Derrick et al. (ZEUS Collab.)</td></tr><tr><td>RIZZO</td><td>93</td><td>PL B337 128</td><td>T.G. Rizzo (ANL)</td></tr><tr><td>SEVERIJNS</td><td>93</td><td>PRL 73 611 (errat.)</td><td>N. Severijns et al. (LOUV, WISC, LEUV+)</td></tr><tr><td>Also</td><td>93</td><td>PRL 73 611 (errat.)</td><td>N. Severijns et al. (LOUV, WISC, LEUV+)</td></tr><tr><td>STERNER</td><td>93</td><td>PL B303 385</td><td>K. Sternert et al. (AMY Collab.)</td></tr><tr><td>ABREU</td><td>92D</td><td>ZPY C53 555</td><td>P. Abreu et al. (DELPHI Collab.)</td></tr><tr><td>ADRIAN</td><td>92F</td><td>PL B292 472</td><td>O. Adriani et al. (L3 Collab.)</td></tr><tr><td>DECAMP</td><td>92</td><td>PRPL 216 253</td><td>D. Decamp et al. (ALEPH Collab.)</td></tr><tr><td>IMAZATO</td><td>92</td><td>PRL 69 877</td><td>J. Imazato, J. INUS, TOKY+ (SILES)</td></tr><tr><td>MISHRA</td><td>92B</td><td>PL R68 3999</td><td>S.R. Mishra et al. (COLU, CHIC, FNAL+)</td></tr><tr><td>POLAK</td><td>92B</td><td>PL D42 3971</td><td>J.A. Grifolb, M. Masso (BARC, CERN+)</td></tr><tr><td>ACTON</td><td>91</td><td>PL B268 122</td><td>S. Polak, M. Zralek (SILES)</td></tr><tr><td>ACTON</td><td>91B</td><td>PL B273 338</td><td>D.P. Acton et al. (OPAL Collab.)</td></tr><tr><td>ADENA</td><td>91D</td><td>PL B262 155</td><td>B. Adena et al. (OPAL Collab.)</td></tr><tr><td>AQUINO</td><td>91</td><td>PL B261 280</td><td>M. Aquino, A. Fernandez, A. Garcia (CINV, PUEB)</td></tr><tr><td>COLANGELO</td><td>91</td><td>PL B253 154</td><td>P. Colangelo, G. Nardulli (BARI)</td></tr><tr><td>CUYPERS</td><td>91</td><td>PL B259 173</td><td>F. Cuypers, A.F. Falk, P.H. Frampton (DURH, HARV+)</td></tr><tr><td>FARAGGI</td><td>91</td><td>MPL A6 61</td><td>A.E. Faraggi, D.V. Nanopoulos (TAMU)</td></tr><tr><td>POLAK</td><td>91</td><td>NP B363 385</td><td>J. Polak, M. Zralek (SILES)</td></tr><tr><td>RIZZO</td><td>91</td><td>PR D44 202</td><td>T.G. Rizzo (WISC, ISU)</td></tr><tr><td>WALKER</td><td>91</td><td>APJ 376 51</td><td>P. T. Walker et al. (HSCA, OSU, CHIC+)</td></tr><tr><td>ABE</td><td>90F</td><td>PL B246 297</td><td>K. Abe et al. (VENUS Collab.)</td></tr><tr><td>ABE</td><td>90H</td><td>PR D41 2722</td><td>F. Abe et al. (CDF Collab.)</td></tr><tr><td>AKRAWY</td><td>90J</td><td>PL B246 285</td><td>M.Z. Akrawry et al. (OPAL Collab.)</td></tr><tr><td>GONZALEZ...</td><td>90D</td><td>PL B240 163</td><td>M.C. Gonzalez-Garcia, J.W.F. Valle (VALE)</td></tr><tr><td>GRIFOLS</td><td>90D</td><td>PL B331 244</td><td>J.A. Grifolb, E. Masso (JADE)</td></tr><tr><td>GRIFOLS</td><td>90D</td><td>PR D42 3293</td><td>J.A. Grifolb, E. Masso, T.G. Rizzo (BARC, CERN+)</td></tr><tr><td>GIM</td><td>90</td><td>G.N. Kim et al.</td><td>G.N. Kim et al. (AMY Collab.)</td></tr><tr><td>LOPEZ</td><td>90</td><td>PL B240 243</td><td>J.L. Lopez, D.V. Nanopoulos (TAMU)</td></tr><tr><td>BARBIERI</td><td>89B</td><td>PR D39 1229</td><td>R. Barbieri, R.N. Mohapatra (PISA, UMD)</td></tr><tr><td>LANGACKER</td><td>89B</td><td>PR D40 1569</td><td>P. Langacker, S. Uma Sankar (PENN)</td></tr><tr><td>ODAKA</td><td>89</td><td>JPSJ 58 3037</td><td>S. Odaka et al. (VENUS Collab.)</td></tr><tr><td>ROBINETT</td><td>89</td><td>PL D39 834</td><td>R.W. Robinett (PSU)</td></tr><tr><td>ALBAJAR</td><td>88B</td><td>PL B209 127</td><td>C. Albaraj et al. (ALI Collab.)</td></tr><tr><td>BAGGER</td><td>88</td><td>PR D37 1188</td><td>J. Bagger, C. Schmidt, S. King (HARV, BOST)</td></tr><tr><td>BALKE</td><td>88</td><td>PR D37 507</td><td>B. Baake et al. (LBL, UCB, COLO, NWES+)</td></tr><tr><td>BERGSTROM</td><td>88</td><td>PR B212 386</td><td>L. Bergstrom (STO)</td></tr><tr><td>CUYPERS</td><td>88</td><td>PL D60 1237</td><td>F. Wypuers, P.H. Frampton (UNCCH)</td></tr><tr><td>DONCHESKI</td><td>88B</td><td>PL D206 137</td><td>M.A. Doncheski, H. Grotch, R. Robinett (PSU)</td></tr><tr><td>DONCHESKI</td><td>88B</td><td>PR D38 412</td><td>M.A. Doncheski, H. Grotch, R.W. Robinett (PSU)</td></tr><tr><td>BARTEL</td><td>87B</td><td>ZPY C36 15</td><td>W. Bartel et al. (JADE Collab.)</td></tr><tr><td>BEHREND</td><td>86B</td><td>PL B178 452</td><td>H.J. Behrend et al. (CELLO Collab.)</td></tr><tr><td>DERRICK</td><td>86</td><td>PL B66 463</td><td>M. Derrick et al. (HRS Collab.)</td></tr><tr><td>Also</td><td>86</td><td>PR D34 3286</td><td>M. Derrick et al. (HRS Collab.)</td></tr><tr><td>JODIDIO</td><td>86</td><td>PR D34 1967</td><td>A. Jodidio et al. (LBL, NWES, TRIU)</td></tr><tr><td>Also</td><td>86</td><td>PR D34 237 (errat.)</td><td>A. Jodidio et al. (LBL, NWES, TRIU)</td></tr><tr><td>MOHAPATRA</td><td>86</td><td>PR D34 909</td><td>R.N. Mohapatra (UMD)</td></tr><tr><td>ADEVA</td><td>85</td><td>152B 439</td><td>A. Adeva et al. (Mark+ Collab.)</td></tr><tr><td>BERGER</td><td>85B</td><td>ZPY C27 341</td><td>C. Berger et al. (PLUTO Collab.)</td></tr><tr><td>STOKER</td><td>85</td><td>PRL 54 1887</td><td>D.P. Stoker et al. (LBL, NWES, TRIU)</td></tr><tr><td>ADEVA</td><td>84</td><td>PRL 53 134</td><td>B. Adena et al. (Mark-J Collab.)</td></tr><tr><td>BEHREND</td><td>84C</td><td>PL 140B 130</td><td>H.J. Behrend et al. (CELLO Collab.)</td></tr><tr><td>BERGSMA</td><td>83</td><td>PL 122B 465</td><td>F. Bergsma et al. (CHARM Collab.)</td></tr><tr><td>CARR</td><td>83</td><td>J. Carr et al. (LBL, NWES, TRIU)</td><td>J. Carr et al. (LUCI, UCLA)</td></tr><tr><td>BEALL</td><td>82</td><td>PRL 48 848</td><td>G. Beall, M. Bander, A. Soni (TRIU)</td></tr><tr><td>SHANKER</td><td>82</td><td>NP B204 375</td><td>O. Shanker</td></tr></tbody></table>

## Axions ($A^0$) and Other Very Light Bosons, Searches for

See the related review(s):

Axions and Other Similar Particles

### $A^0$ (Axion) MASS LIMITS from Astrophysics and Cosmology

These bounds depend on model-dependent assumptions (i.e. — on a combination of axion parameters).

<table><thead><tr><th>VALUE (MeV)</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>• • •</td><td></td><td></td><td>We do not use the following data for averages, fits, limits, etc. • • •</td></tr><tr><td>>0.2</td><td></td><td></td><td></td></tr><tr><td>>0.25</td><td></td><td></td><td></td></tr><tr><td>>0.2</td><td></td><td></td><td></td></tr></tbody></table>

<table><tbody><tr><td>>0.3</td><td></td><td></td><td>MIKAELIAN</td><td>78</td><td>ASTR</td><td>Stellar emission</td></tr><tr><td>>0.2</td><td></td><td></td><td>2 SATO</td><td>78</td><td>ASTR</td><td>Standard Axion</td></tr><tr><td></td><td></td><td></td><td>VYSOTSKII</td><td>78</td><td>ASTR</td><td>Standard Axion</td></tr></tbody></table>

¹ Lower bound from 5.5 MeV γ-ray line from the sun.

² Lower bound from requiring the red giants' stellar evolution not be disrupted by axion emission.

### $A^0$ (Axion) and Other Light Boson ($X^0$) Searches in Hadron Decays

Limits are for branching ratios.

<table><thead><tr><th>VALUE</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>&lt;4 × 10<sup>-8</sup></td><td>95</td><td>1 ADACHI</td><td>23k BEL2</td><td>B<sup>+</sup> → K<sup>+</sup>X<sup>0</sup></td></tr><tr><td>&lt;9 × 10<sup>-8</sup></td><td>95</td><td>2 ADACHI</td><td>23k BEL2</td><td>B<sup>0</sup> → K<sup>+</sup>(892)<sup>0</sup>X<sup>0</sup></td></tr><tr><td>&lt;3.7 × 10<sup>-10</sup></td><td>95</td><td>3 CORTINA-GIL</td><td>23b NA62</td><td>K<sup>+</sup> → π<sup>+</sup>A<sup>0</sup>X<sup>0</sup>, A<sup>0</sup> → (K<sup>*</sup>(892)<sup>0</sup>) → K<sup>+</sup>π<sup>-</sup></td></tr><tr><td>&lt;4.2 × 10<sup>-8</sup></td><td>95</td><td>4 LEES</td><td>22b BABR</td><td>B<sup>±</sup> → K<sup>±</sup>A<sup>0</sup>(A<sup>0</sup> → γγ)</td></tr><tr><td>&lt;7 × 10<sup>-13</sup></td><td>90</td><td>5 ABRATENKO</td><td>21 MCBN</td><td>K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>&lt;1.5 × 10<sup>-7</sup></td><td>90</td><td>6 CORTINA-GIL</td><td>21 NA62</td><td>K<sup>+</sup> → μ<sup>+</sup>νX<sup>0</sup></td></tr><tr><td>&lt;5 × 10<sup>-11</sup></td><td>90</td><td>7 CORTINA-GIL</td><td>21 NA62</td><td>K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup></td></tr><tr><td>&lt;9 × 10<sup>-10</sup></td><td>90</td><td>8 CORTINA-GIL</td><td>21c NA62</td><td>K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup></td></tr><tr><td>&lt;1.5 × 10<sup>-8</sup></td><td>90</td><td>9 PARK</td><td>21 BELL</td><td>B<sup>0</sup> → X<sup>0</sup>X<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>, μ<sup>+</sup>μ<sup>-</sup>π<sup>+</sup>π<sup>-</sup>)</td></tr><tr><td>&lt;2.4 × 10<sup>-9</sup></td><td>90</td><td>10 AHN</td><td>19 KOTO</td><td>K<sup>0</sup><sub>L</sub> → π<sup>0</sup>X<sup>0</sup>, m<sup>X0</sup> = 135 MeV</td></tr><tr><td>&lt;2 × 10<sup>-10</sup></td><td>90</td><td>11 AAIJ</td><td>17AQ LHCB</td><td>K<sup>+</sup> → K<sup>+</sup>X<sup>0</sup>(X<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup>)</td></tr><tr><td>&lt;3.7 × 10<sup>-8</sup></td><td>95</td><td>12 AHN</td><td>17 KOTO</td><td>K<sup>0</sup><sub>L</sub> → π<sup>0</sup>X<sup>0</sup>, m<sup>X0</sup> = 135 MeV</td></tr><tr><td>&lt;6 × 10<sup>-11</sup></td><td>90</td><td>13 BATLEY</td><td>17 NA48</td><td>K<sup>±</sup> → π<sup>±</sup>X<sup>0</sup>(X<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup>)</td></tr><tr><td>&lt;1 × 10<sup>-9</sup></td><td>95</td><td>16 WON</td><td>16 BELL</td><td>η → γX<sup>0</sup>(X<sup>0</sup> → π<sup>+</sup>π<sup>-</sup>)</td></tr><tr><td>&lt;1.5 × 10<sup>-6</sup></td><td>90</td><td>15 AAIJ</td><td>15AZ LHCB</td><td>B<sup>0</sup> → K<sup>+</sup>X<sup>0</sup>(X<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup>)</td></tr><tr><td>&lt;2 × 10<sup>-8</sup></td><td>90</td><td>16 ADLARSON</td><td>13 WASA</td><td>π<sup>0</sup> → γX<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>, m<sup>X0</sup> = 100 MeV)</td></tr><tr><td>&lt;3.3 × 10<sup>-5</sup></td><td>90</td><td>17 BABUSCI</td><td>13B KLOE</td><td>φ → ηX<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>&lt;5.0 × 10<sup>-8</sup></td><td>90</td><td>18 ARCHILLI</td><td>12 KLOE</td><td>φ → ηX<sup>0</sup>, X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup></td></tr><tr><td>&lt;5.2 × 10<sup>-10</sup></td><td>90</td><td>19 GNINENKO</td><td>12a BDMP</td><td>π<sup>0</sup> → γX<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>&lt;2.8 × 10<sup>-4</sup></td><td>90</td><td>20 GNINENKO</td><td>12b BDMP</td><td>η(η<sup>′</sup>) → γX<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>&lt;3 × 10<sup>-4</sup></td><td>90</td><td>21 ADLER</td><td>04 B787</td><td>K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup></td></tr><tr><td>&lt;4 × 10<sup>-5</sup></td><td>90</td><td>22 ANISIMOVSK...04</td><td>B949</td><td>K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup></td></tr><tr><td>&lt;4.9 × 10<sup>-5</sup></td><td>90</td><td>23 ADLER</td><td>02c B787</td><td>K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup></td></tr><tr><td>&lt;5.3 × 10<sup>-5</sup></td><td>90</td><td>24 ADLER</td><td>01 B787</td><td>K<sup>+</sup> → π<sup>+</sup>π<sup>0</sup>A<sup>0</sup></td></tr><tr><td>&lt;3.3 × 10<sup>-5</sup></td><td>90</td><td>25 ALTEGOER</td><td>98 NOMD</td><td>π<sup>0</sup> → γX<sup>0</sup>, m<sup>X0</sup> &lt; 120 MeV</td></tr><tr><td>&lt;5.0 × 10<sup>-8</sup></td><td>90</td><td>26 KITCHING</td><td>97 B787</td><td>K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup>(X<sup>0</sup> → γγ)</td></tr><tr><td>&lt;5.2 × 10<sup>-10</sup></td><td>90</td><td>27 ADLER</td><td>96 B787</td><td>K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup></td></tr><tr><td>&lt;2.8 × 10<sup>-4</sup></td><td>90</td><td>28 AMSLER</td><td>96B CBAR</td><td>π<sup>0</sup> → γX<sup>0</sup>, m<sup>X0</sup> &lt; 65 MeV</td></tr><tr><td>&lt;3 × 10<sup>-4</sup></td><td>90</td><td>28 AMSLER</td><td>96B CBAR</td><td>η → γX<sup>0</sup>, m<sup>X0</sup> = 50-200 MeV</td></tr><tr><td>&lt;4 × 10<sup>-5</sup></td><td>90</td><td>28 AMSLER</td><td>96b CBAR</td><td>η<sup>′</sup> → γX<sup>0</sup>, m<sup>X0</sup> = 50-925 MeV</td></tr><tr><td>&lt;6 × 10<sup>-5</sup></td><td>90</td><td>28 AMSLER</td><td>94b CBAR</td><td>π<sup>0</sup> → γX<sup>0</sup>, m<sup>X0</sup> = 65-125 MeV</td></tr><tr><td>&lt;6 × 10<sup>-5</sup></td><td>90</td><td>28 AMSLER</td><td>94b CBAR</td><td>η → γX<sup>0</sup>, m<sup>X0</sup> = 200-525 MeV</td></tr><tr><td>&lt;7 × 10<sup>-3</sup></td><td>90</td><td>29 MEIJERDREES 94</td><td>CNTR</td><td>π<sup>0</sup> → γX<sup>0</sup>, m<sup>X0</sup> = 25 MeV</td></tr><tr><td>&lt;2 × 10<sup>-3</sup></td><td>90</td><td>29 MEIJERDREES 94</td><td>CNTR</td><td>π<sup>0</sup> → γX<sup>0</sup>, m<sup>X0</sup> = 100 MeV</td></tr><tr><td>&lt;2 × 10<sup>-7</sup></td><td>90</td><td>30 ATIYA</td><td>93b B787</td><td>Sup. by ADLER 04</td></tr><tr><td>&lt;3 × 10<sup>-13</sup></td><td>90</td><td>31 NG</td><td>93 COSM</td><td>π<sup>0</sup> → γX<sup>0</sup></td></tr><tr><td>&lt;1.1 × 10<sup>-8</sup></td><td>90</td><td>32 ALLIEGRO</td><td>92 SPEC</td><td>K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>&lt;5 × 10<sup>-4</sup></td><td>90</td><td>33 ATIYA</td><td>92 B787</td><td>π<sup>0</sup> → γX<sup>0</sup></td></tr><tr><td>&lt;1 × 10<sup>-12</sup></td><td>95</td><td>34 BARABASH</td><td>92 BDMP</td><td>π<sup>±</sup> → e<sup>±</sup>νX<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>, γγ), m<sup>X0</sup> = 8 MeV</td></tr><tr><td>&lt;1 × 10<sup>-12</sup></td><td>95</td><td>35 BARABASH</td><td>92 BDMP</td><td>K<sup>±</sup> → π<sup>±</sup>X<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>, γγ), m<sup>X0</sup> = 10 MeV</td></tr><tr><td>&lt;1 × 10<sup>-11</sup></td><td>95</td><td>36 BARABASH</td><td>92 BDMP</td><td>K<sup>0</sup><sub>L</sub> → π<sup>0</sup>X<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>, γγ), m<sup>X0</sup> = 10 MeV</td></tr><tr><td>&lt;1 × 10<sup>-14</sup></td><td>95</td><td>37 BARABASH</td><td>92 BDMP</td><td>η → ηX<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>, γγ), m<sup>X0</sup> = 10 MeV</td></tr><tr><td>&lt;4 × 10<sup>-6</sup></td><td>90</td><td>38 MEIJERDREES 92</td><td>SPEC</td><td>π<sup>0</sup> → γX<sup>0</sup>(X<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>, m<sup>X0</sup> = 100 MeV)</td></tr><tr><td>&lt;1 × 10<sup>-7</sup></td><td>90</td><td>39 ATIYA</td><td>90b B787</td><td>Sup. by KITCHING 97</td></tr><tr><td>&lt;1.3 × 10<sup>-8</sup></td><td>90</td><td>40 KORENCHE...</td><td>87 SPEC</td><td>π<sup>+</sup> → e<sup>+</sup>νA<sup>0</sup>(A<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>&lt;1 × 10<sup>-9</sup></td><td>90</td><td>41 EICHLER</td><td>86 SPEC</td><td>Stopped π<sup>+</sup> → e<sup>+</sup>νA<sup>0</sup></td></tr><tr><td>&lt;2 × 10<sup>-5</sup></td><td>90</td><td>42 YAMAZAKI</td><td>84 SPEC</td><td>For 160<m&lt;260 MeV</td></tr><tr><td>&lt;(1.5×4) × 10<sup>-6</sup></td><td>90</td><td>42 YAMAZAKI</td><td>84 SPEC</td><td>K decay, m<sup>X0</sup> ≪ 100 MeV</td></tr><tr><td></td><td></td><td>43 ASANO</td><td>82 CNTR</td><td>Stopped K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup></td></tr><tr><td></td><td></td><td>44 ASANO</td><td>81b CNTR</td><td>Stopped K<sup>+</sup> → π<sup>+</sup>X<sup>0</sup></td></tr><tr><td></td><td></td><td>45 ZHITNITSKII</td><td>79</td><td>Heavy axion</td></tr></tbody></table>

¹ ADACHI 23k quoted limit is for $m_{X^0} \approx 3$ GeV, $\tau_{X^0} = 1$ cm, and the decay channel $X^0 \to e^+e^-$. See their Fig. 2 for limits with different lifetimes and decay channels, $X^0 \to \mu^+\mu^-$, $\pi^+\pi^-$, $K^+K^-$.

² ADACHI 23k quoted limit is for $m_{X^0} \approx 2$ GeV, $\tau_{X^0} = 1$ cm, and the decay channel $X^0 \to e^+e^-$. See their Fig. 2 for limits with different lifetimes and decay channels, $X^0 \to \mu^+\mu^-$, $\pi^+\pi^-$, $K^+K^-$.

³ CORTINA-GIL 23b limit extends over 10-170 MeV in mass. Quoted limit is at 155 MeV.
# Gauge & Higgs Boson Particle Listings
## Axions ($A^0$) and Other Very Light Bosons

⁴LEES 22B quoted limit is for $m_{A^0} = 3.9$ GeV, assuming the promptly decaying axion. Limits of $O(10^{-7})$ are obtained for $m_{A^0} = 0.175-4.78$ GeV. See their Figs.3 and 4 for mass and lifetime dependent limits.

⁵ABRATENKO 21 quoted limit is for $m_{\chi^0} = 150$ MeV and the lifetime $\tau_{\chi^0} = 80$ m. See their Fig. 4 for the limits in the range of $m_{\chi^0} = 10-210$ MeV.

⁶CORTINA-GIL 21 quoted limit is for $m_{\chi^0} = 370$ MeV. Limits from $O(10^{-5})$ and $O(10^{-6})$ are obtained for $m_{\chi^0} = 10-370$ MeV (see their Fig. 7).

⁷CORTINA-GIL 21A quoted limit is for $m_{\chi^0} = 160-250$ MeV. Limits between $5 \times 10^{-11}$ and $2 \times 10^{-10}$ are obtained in the range of $m_{\chi^0} = 0-110$ and $154-260$ MeV, assuming stable or invisibly decaying $\chi^0$. See their Fig. 4 for mass- and lifetime-dependent limits.

⁸CORTINA-GIL 21C quoted limit is for $m_{\chi^0} = 130-140$ MeV, and limits of $9 \times 10^{-10}-6 \times 10^{-7}$ are obtained in the mass range of $m_{\chi^0} = 110-155$ MeV, assuming $\chi^0$ escapes detection. See their Fig. 6 for mass- and lifetime-dependent limits.

⁹PARK 21 look for dark photons produced by decays of $B^0$ through off-shell Higgs-dark Higgs mixing. See their Fig. 5 for limits in the range of $m_{\chi^0} = 0.01-2.62$ GeV.

¹⁰AHN 19 is an update of AHN 17 from a new data set. See their Fig. 4 for the limits in the range of $m_{\chi^0} = 0-250$ MeV.

¹¹AAIJ 17AQ limit is for $\tau_{\chi^0} = 10$ ps. See their Fig. 4 for limits in the range of $m_{\chi^0} = 250-4700$ MeV and $\tau_{\chi^0} = 0.1-1000$ ps.

¹²AHN 17 limit as a function of $m_{\chi^0}$ from 0 to 250 MeV is provided in their Fig. 5.

¹³BATLEY 17 limit is for $m_{\chi^0} = 216$ MeV and $\tau_{\chi^0} \le 10$ ps. See their Fig. 4(c) for limits in the range of $m_{\chi^0} = 211-354$ MeV and longer lifetimes.

¹⁴WON 16 look for a vector boson coupled to baryon number. Derived limits on $a'$ between $10^{-3}-10^{-2}$ for $m_{\chi^0} = 290-520$ MeV at 95% CL. See their Fig. 4 for mass-dependent limits.

¹⁵AAIJ 15Az limit is for $\tau_{\chi^0} = 10$ ps and $m_{\chi^0} = 214-4350$ MeV. See their Fig. 4 for mass- and lifetime-dependent limits.

¹⁶ADLARSON 13 limits between $2.0 \times 10^{-5}$ and $1.5 \times 10^{-6}$ are obtained for $m_{\chi^0} = 24-100$ MeV (see their Fig. 8). Angular momentum conservation requires that $\chi^0$ has spin $\ge 1$.

¹⁷BABUSCI 13B limit is for $B(\phi \to \eta\chi^0)B(\chi^0 \to e^+e^-)$ and applies to $m_{\chi^0} = 410$ MeV. It is derived by analyzing $\eta \to \pi^0\pi^0\pi^0$ and $\pi^0\pi^+\pi^0$. Limits between $1 \times 10^{-6}$ and $2 \times 10^{-8}$ are obtained for $m_{\chi^0} \le 450$ MeV (see their Fig. 6).

¹⁸ARCHILLI 12 analyzed $\eta \to \pi^+\pi^-\pi^0$ decays. Derived limits on $\alpha'/\alpha < 2 \times 10^{-5}$ for $m_{\chi^0} = 50-420$ MeV at 90% CL. See their Fig. 8 for mass-dependent limits.

¹⁹GNINENKO 12A limit is for $B(\pi^0 \to \gamma\chi^0)B(\chi^0 \to e^+e^-)$ and applies for $m_{\chi^0} = 90$ MeV and $\tau_{\chi^0} \simeq 1 \times 10^{-8}$ sec. Limits between $10^{-8}$ and $2 \times 10^{-15}$ are obtained for $m_{\chi^0} = 3-120$ MeV and $\tau_{\chi^0} = 1 \times 10^{-11}-1$ sec. See their Fig. 3 for limits at different masses and lifetimes.

²⁰GNINENKO 12B limit is for $B(\eta \to \gamma\chi^0)B(\chi^0 \to e^+e^-)$ and applies for $m_{\chi^0} = 100$ MeV and $\tau_{\chi^0} \simeq 6 \times 10^{-9}$ sec. Limits between $10^{-5}$ and $3 \times 10^{-14}$ are obtained for $m_{\chi^0} \lesssim 550$ MeV and $\tau_{\chi^0} = 10^{-10}-10$ sec. See their Fig. 5 for limits at different mass and lifetime and for $\eta'$ decays.

²¹ADLER 04 limit applies for a mass near 180 MeV. For other masses in the range $m_{\chi^0} = 150-250$ MeV the limit is less restrictive, but still improves ADLER 02c and ATIYA 93B.

²²ANISIMOVSKY 04 bound is for $m_{\chi^0} = 0$.

²³ADLER 02c bound is for $m_{\chi^0} < 60$ MeV. See Fig. 2 for limits at higher masses.

²⁴The quoted limit is for $m_{\chi^0} = 0-80$ MeV. See their Fig. 5 for the limit at higher mass. The branching fraction limit assumes pure phase space decay distributions.

²⁵ALTEGOER 98 looked for $\chi^0$ from $\pi^0$ decay which penetrate the shielding and convert to $\pi^0$ in the external Coulomb field of a nucleus.

²⁶KITCHING 97 limit is for $B(K^+ \to \pi^+\chi^0)B(\chi^0 \to \gamma\gamma)$ and applies for $m_{\chi^0} \simeq 50$ MeV, $\tau_{\chi^0} < 10^{-10}$ s. Limits are provided for $0<m_{\chi^0} < 100$ MeV, $\tau_{\chi^0} < 10^{-8}$ s.

²⁷ADLER 96 looked for a peak in missing-mass distribution. This work is an update of ATIYA 93. The limit is for massless stable $\chi^0$ particles and extends to $m_{\chi^0} = 80$ MeV at the same level. See paper for dependence on finite lifetime.

²⁸AMSLER 94B and AMSLER 96B looked for a peak in missing-mass distribution.

²⁹MEIJERDREES 94 limit is based on inclusive photon spectrum and is independent of $\chi^0$ decay modes. It applies to $\tau_{\chi^0} > 10^{-23}$ sec.

³⁰ATIYA 93B looked for a peak in missing mass distribution. The bound applies for stable $\chi^0$ of $m_{\chi^0} = 150-250$ MeV, and the limit becomes stronger ($10^{-8}$) for $m_{\chi^0} = 180-240$ MeV.

³¹NG 93 studied the production of $\chi^0$ via $\gamma\gamma \to \pi^0 \to \gamma\chi^0$ in the early universe at $T \simeq 1$ MeV. The bound on extra neutrinos from nucleosynthesis $\Delta N_b < 0.3$ (WALKER 91) is employed. It applies to $m_{\chi^0} \ll 1$ MeV in order to be relativistic down to nucleosynthesis temperature. See paper for heavier $\chi^0$.

³²ALLIEGRO 92 limit applies for $m_{\chi^0} = 150-340$ MeV and is the branching ratio times the decay probability. Limit is $< 1.5 \times 10^{-8}$ at 99%CL.

³³ATIYA 92 looked for a peak in missing mass distribution. The limit applies to $m_{\chi^0} = 0-130$ MeV in the narrow resonance limit. See paper for the dependence on lifetime. Covariance requires $\chi^0$ to be a vector particle.

³⁴BARABASH 92 is a beam dump experiment that searched for a light Higgs. Limits between $1 \times 10^{-12}$ and $1 \times 10^{-7}$ are obtained for $3 < m_{\chi^0} < 40$ MeV.

³⁵Limits between $1 \times 10^{-12}$ and 1 are obtained for $4 < m_{\chi^0} < 69$ MeV.

³⁶Limits between $1 \times 10^{-11}$ and $5 \times 10^{-3}$ are obtained for $4 < m_{\chi^0} < 63$ MeV.

³⁷Limits between $1 \times 10^{-14}$ and 1 are obtained for $3 < m_{\chi^0} < 82$ MeV.

³⁸MEIJERDREES 92 limit applies for $\tau_{\chi^0} = 10^{-23}-10^{-11}$ sec. Limits between $2 \times 10^{-4}$ and $4 \times 10^{-6}$ are obtained for $m_{\chi^0} = 25-120$ MeV. Angular momentum conservation requires that $\chi^0$ has spin $\ge 1$.

³⁹ATIYA 90B limit is for $B(K^+ \to \pi^+\chi^0)B(\chi^0 \to \gamma\gamma)$ and applies for $m_{\chi^0} = 50$ MeV, $\tau_{\chi^0} < 10^{-10}$ s. Limits are also provided for $0 < m_{\chi^0} < 100$ MeV, $\tau_{\chi^0} < 10^{-8}$ s.

⁴⁰KORENCHENKO 87 limit assumes $m_{A^0} = 1.7$ MeV, $\tau_{A^0} \lesssim 10^{-12}$ s, and $B(A^0 \to e^+e^-) = 1$.

⁴¹EICHLER 86 looked for $\pi^+ \to e^+\nu A^0$ followed by $A^0 \to e^+e^-$. Limits on the branching fraction depend on the mass and lifetime of $A^0$. The quoted limits are valid when $\tau(A^0) \gtrsim 3. \times 10^{-10}$ s if the decays are kinematically allowed.

⁴²YAMAZAKI 84 looked for a discrete line in $K^+ \to \pi^+X$. Sensitive to wide mass range (5-300 MeV), independent of whether X decays promptly or not.

⁴³ASANO 82 at KEK set limits for $B(K^+ \to \pi^+\chi^0)$ for $m_{\chi^0} < 100$ MeV as BR $< 4 \times 10^{-8}$ for $\tau(\chi^0 \to n\gamma's) > 1 \times 10^{-9}$ s, BR $< 1.4 \times 10^{-6}$ for $\tau < 1 \times 10^{-9}$ s.

⁴⁴ASANO 81B is KEK experiment. Set $B(K^+ \to \pi^+\chi^0) < 3.8 \times 10^{-8}$ at CL = 90%.

⁴⁵ZHITNITSKII 79 argue that a heavy axion predicted by YANG 78 ($3 < m < 40$ MeV) contradicts experimental muon anomalous magnetic moments.

## A⁰ (Axion) Searches in Quarkonium Decays

Decay or transition of quarkonium. Limits are for branching ratio.

<table><thead><tr><th>VALUE</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>&lt;8.3 &times; 10<sup>-8</sup></td><td>95</td><td>1 ABLIKIM</td><td>23E BES3</td><td>J/ψ &rarr; A<sup>0</sup>γ (A<sup>0</sup> &rarr; γγ)</td></tr><tr><td>&lt;3.1 &times; 10<sup>-7</sup></td><td>90</td><td>2 JIA</td><td>22 BELL</td><td>T(15) &rarr; A<sup>0</sup>γ(A<sup>0</sup> &rarr; μ<sup>+</sup>μ<sup>-</sup>)</td></tr><tr><td>&lt;2.8 &times; 10<sup>-8</sup></td><td>90</td><td>3 ABLIKIM</td><td>16E BES3</td><td>J/ψ &rarr; A<sup>0</sup>γ (A<sup>0</sup> &rarr; μ<sup>+</sup>μ<sup>-</sup>)</td></tr><tr><td>&lt;4 &times; 10<sup>-7</sup></td><td>90</td><td>4 ABLIKIM</td><td>12 BES3</td><td>J/ψ &rarr; A<sup>0</sup>γ (A<sup>0</sup> &rarr; μ<sup>+</sup>μ<sup>-</sup>)</td></tr><tr><td>&lt;4.0 &times; 10<sup>-5</sup></td><td>90</td><td>5 ANTREASYAN 90C</td><td>CBAL</td><td>T(15) &rarr; A<sup>0</sup>γ</td></tr><tr><td>&lt;5 &times; 10<sup>-5</sup></td><td>90</td><td>6 DRUZHININ</td><td>87 ND</td><td>φ &rarr; A<sup>0</sup>γ (A<sup>0</sup> &rarr; e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>&lt;2 &times; 10<sup>-3</sup></td><td>90</td><td>7 DRUZHININ</td><td>87 ND</td><td>φ &rarr; A<sup>0</sup>γ (A<sup>0</sup> &rarr; γγ)</td></tr><tr><td>&lt;7 &times; 10<sup>-6</sup></td><td>90</td><td>8 DRUZHININ</td><td>87 ND</td><td>φ &rarr; A<sup>0</sup>γ (A<sup>0</sup> &rarr; missing)</td></tr><tr><td>&lt;1.4 &times; 10<sup>-5</sup></td><td>90</td><td>9 EDWARDS</td><td>82 CBAL</td><td>J/ψ &rarr; A<sup>0</sup>γ</td></tr></tbody></table>

¹ABLIKIM 23E obtained limits in the range of $8.3 \times 10^{-8}-1.8 \times 10^{-6}$ for 0.165 GeV $\le m_{A^0} \le 2.84$ GeV. See their Fig. 5 for mass-dependent limits.

²JIA 22 limits between $3.1 \times 10^{-7}-1.6 \times 10^{-5}$ were obtained for 0.22 GeV $< m_{A^0} < 9.2$ GeV. See their Fig. 4 for mass-dependent limits.

³ABLIKIM 16E limits between $2.8-495.3 \times 10^{-8}$ were obtained for 0.212 GeV $< m_{A^0} < 3.0$ GeV. See their Fig. 5 for mass-dependent limits.

⁴ABLIKIM 12 derived limits between $4 \times 10^{-7}-2.1 \times 10^{-5}$ for 0.212 GeV $< m_{A^0} < 3.0$ GeV. See their Fig. 2(c) for mass-dependent limits.

⁵ANTREASYAN 90C assume that $A^0$ does not decay in the detector.

⁶The first DRUZHININ 87 limit is valid when $\tau_{A^0}/m_{A^0} < 3 \times 10^{-13}$ s/MeV and $m_{A^0} < 20$ MeV.

⁷The second DRUZHININ 87 limit is valid when $\tau_{A^0}/m_{A^0} < 5 \times 10^{-13}$ s/MeV and $m_{A^0} < 20$ MeV.

⁸The third DRUZHININ 87 limit is valid when $\tau_{A^0}/m_{A^0} > 7 \times 10^{-12}$ s/MeV and $m_{A^0} < 200$ MeV.

⁹EDWARDS 82 looked for $J/\psi \to \gamma A^0$ decays by looking for events with a single $\gamma$ [of energy $\sim 1/2$ the $J/\psi(1S)$ mass], plus nothing else in the detector. The limit is inconsistent with the axion interpretation of the FAISSNER 81B result.

## A⁰ (Axion) Searches in Positronium Decays

Decay or transition of positronium. Limits are for branching ratio.

<table><thead><tr><th>VALUE</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>&lt;4.4 &times; 10<sup>-5</sup></td><td>90</td><td>1 BADERT...</td><td>02 CNTR</td><td>o-Ps &rarr; &gamma;X<sub>1</sub>X<sub>2</sub>, m<sub>X<sub>1</sub></sub> + m<sub>X<sub>2</sub></sub> &le; 900 keV</td></tr><tr><td>&lt;2 &times; 10<sup>-4</sup></td><td>90</td><td>MAENO</td><td>95 CNTR</td><td>o-Ps &rarr; A<sup>0</sup>γ, m<sub>A<sup>0</sup></sub>=850-1013 keV</td></tr><tr><td>&lt;3.0 &times; 10<sup>-4</sup></td><td>90</td><td>2 ASAI</td><td>94 CNTR</td><td>o-Ps &rarr; A<sup>0</sup>γ, m<sub>A<sup>0</sup></sub>=30-500 keV</td></tr><tr><td>&lt;2.8 &times; 10<sup>-5</sup></td><td>90</td><td>3 AKOPYAN</td><td>91 CNTR</td><td>o-Ps &rarr; A<sup>0</sup>γ, m<sub>A<sup>0</sup></sub> = 30 keV</td></tr><tr><td>&lt;1.1 &times; 10<sup>-6</sup></td><td>90</td><td>4 ASAI</td><td>91 CNTR</td><td>o-Ps &rarr; A<sup>0</sup>γ, m<sub>A<sup>0</sup></sub> &le; 800 keV</td></tr><tr><td>&lt;3.8 &times; 10<sup>-4</sup></td><td>90</td><td>GNINENKO</td><td>90 CNTR</td><td>o-Ps &rarr; A<sup>0</sup>γ, m<sub>A<sup>0</sup></sub> &le; 30 keV</td></tr><tr><td>&lt;(1-5) &times; 10<sup>-4</sup></td><td>95</td><td>5 TSHUCHIAKI</td><td>90 CNTR</td><td>o-Ps &rarr; A<sup>0</sup>γ, m<sub>A<sup>0</sup></sub> = 300-900 keV</td></tr><tr><td>&lt;6.4 &times; 10<sup>-5</sup></td><td>90</td><td>6 ORITO</td><td>89 CNTR</td><td>o-Ps &rarr; A<sup>0</sup>γ, m<sub>A<sup>0</sup></sub> &le; 30 keV</td></tr><tr><td></td><td></td><td>7 AMALDI</td><td>85 CNTR</td><td>Ortho-positronium</td></tr><tr><td></td><td></td><td>8 CARBONI</td><td>83 CNTR</td><td>Ortho-positronium</td></tr></tbody></table>

¹BADERTSCHER 02 looked for a three-body decay of ortho-positronium into a photon and two penetrating (neutral or milli-charged) particles.

²The ASA1 94 limit is based on inclusive photon spectrum and is independent of $A^0$ decay modes.

³The AKOPYAN 91 limit applies for a short-lived $A^0$ with $\tau_{A^0} < 10^{-13}$ $m_{A^0}$ [keV] s.

⁴ASA1 91 limit translates to $g_{A^0 e^+e^-}^2 / 4\pi < 1.1 \times 10^{-11}$ (90% CL) for $m_{A^0} < 800$ keV.

⁵The TSHUCHIAKI 90 limit is based on inclusive photon spectrum and is independent of $A^0$ decay modes.

⁶ORITO 89 limit translates to $g_{A^0 ee^-}^2 / 4\pi < 6.2 \times 10^{-10}$. Somewhat more sensitive limits are obtained for larger $m_{A^0}$: $B < 7.6 \times 10^{-6}$ at 100 keV.

⁷AMALDI 85 set limits $B(A^0\gamma) / B(\gamma\gamma\gamma) < (1-5) \times 10^{-6}$ for $m_{A^0} = 900-100$ keV which are about 1/10 of the CARBONI 83 limits.

⁸CARBONI 83 looked for orthopositronium $\to A^0\gamma$. Set limit for $A^0$ electron coupling squared, $g(eeA^0)^2 / (4\pi) < 6. \times 10^{-10}-7. \times 10^{-9}$ for $m_{A^0}$ from 150-900 keV (CL = 99.7%). This is about 1/10 of the bound from $g-2$ experiments.
A⁰ (Axion) Search in Photoproduction

<table><thead><tr><th>VALUE</th><th>DOCUMENT ID</th><th>TECN.</th><th>COMMENT</th></tr></thead></table>

• • • We do not use the following data for averages, fits, limits, etc. • • •

1 ADHIKARI 22c GLUX $m_{A^0} = 180-480, 600-720$ MeV

2 BASSOMPIE... 95 $m_{A^0} = 1.8 \pm 0.2$ MeV

¹ ADHIKARI 22c search for $A^0 \to \gamma\gamma$ and $A^0 \to \pi^+\pi^-\pi^0$ decays, and set limits of $f_{A^0} \sim 0.5-14$ GeV at 90% CL. See their Fig. 4 for mass-dependent limits.

² BASSOMPIERRE 95 is an extension of BASSOMPIERRE 93. They looked for a peak in the invariant mass of $e^+e^-$ pairs in the region $m_{e^+e^-} = 1.8 \pm 0.2$ MeV. They obtained bounds on the production rate $A^0$ for $\tau(A^0) = 10^{-18}-10^{-9}$ sec. They also found an excess of events in the range $m_{e^+e^-} = 2.1-3.5$ MeV.

A⁰ (Axion) Production in Hadron Collisions

Limits are for $\sigma(A^0)/\sigma(\pi^0)$.

<table><thead><tr><th>VALUE</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN.</th><th>COMMENT</th></tr></thead></table>

• • • We do not use the following data for averages, fits, limits, etc. • • •

<table><tbody><tr><td>1</td><td>ACCIARRI</td><td>23</td><td>ARNT</td><td>A<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup></td></tr><tr><td>2</td><td>BERTUZZO</td><td>23</td><td>ARNT</td><td>A<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup></td></tr><tr><td>3</td><td>AAD</td><td>22J</td><td>ATLS</td><td>H → A<sup>0</sup>A<sup>0</sup>, ZA<sup>0</sup><br>(A<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup>)</td></tr><tr><td>4</td><td>TUMASYAN</td><td>22AH</td><td>CMS</td><td>H → A<sup>0</sup>A<sup>0</sup>, A<sup>0</sup> →<br>e<sup>+</sup>e<sup>-</sup>, μ<sup>+</sup>μ<sup>-</sup></td></tr><tr><td>5</td><td>TUMASYAN</td><td>22R</td><td>CMS</td><td>pp → A<sup>*0</sup>μ<sup>+</sup>μ<sup>-</sup>, ZH</td></tr><tr><td>6</td><td>AAD</td><td>21F</td><td>ATLS</td><td>Monojet + missing p<sub>T</sub></td></tr><tr><td>7</td><td>AAD</td><td>21k</td><td>ATLS</td><td>Mono-γ + missing p<sub>T</sub></td></tr><tr><td>8</td><td>AAD</td><td>21n</td><td>ATLS</td><td>γγ scatt. in Pb+Pb</td></tr><tr><td>9</td><td>CARRA</td><td>21</td><td>ATLS</td><td>pp → A<sup>*0</sup> → WW, Zγ</td></tr><tr><td>10</td><td>AAIJ</td><td>20AL</td><td>LHCB</td><td>pp → X<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup></td></tr><tr><td>11</td><td>GAVELA</td><td>20</td><td>CMS</td><td>pp → A<sup>*0</sup> → γγ, ZZ</td></tr><tr><td>12</td><td>SIRUNYAN</td><td>19BQ</td><td>CMS</td><td>X<sup>0</sup> → μ<sup>+</sup>μ<sup>-</sup></td></tr><tr><td>13</td><td>JAIN</td><td>07</td><td>CNTR</td><td>A<sup>0</sup> → e<sup>+</sup>e<sup>-</sup></td></tr><tr><td>14</td><td>AHMAD</td><td>97</td><td>SPEC</td><td>e<sup>+</sup> production</td></tr><tr><td>15</td><td>LEINBERGER</td><td>97</td><td>SPEC</td><td>A<sup>0</sup> → e<sup>+</sup>e<sup>-</sup></td></tr><tr><td>16</td><td>GANZ</td><td>96</td><td>SPEC</td><td>A<sup>0</sup> → e<sup>+</sup>e<sup>-</sup></td></tr><tr><td>17</td><td>KAMEL</td><td>96</td><td>EMUL</td><td>32S emulsion, A<sup>0</sup> →</td></tr><tr><td>18</td><td>BLUEMLEIN</td><td>92</td><td>BDMP</td><td>A<sup>0</sup>N<sup>→</sup> ℓ<sup>+</sup>ℓ<sup>-</sup>N<sup>→</sup></td></tr><tr><td>19</td><td>MEIJERDREES<sup>92</sup></td><td>SPEC</td><td>π<sup>-</sup>p → nA<sup>0</sup>, A<sup>0</sup> →</td></tr><tr><td>20</td><td>BLUEMLEIN</td><td>91</td><td>BDMP</td><td>A<sup>0</sup> → e<sup>+</sup>e<sup>-</sup>, 2γ</td></tr><tr><td>21</td><td>FAISSNER</td><td>89</td><td>OSPK</td><td>Beam dump,</td></tr><tr><td>22</td><td>DEBOER</td><td>88</td><td>RVUE</td><td>A<sup>0</sup> → e<sup>+</sup>e<sup>-</sup></td></tr><tr><td>23</td><td>EL-NADI</td><td>88</td><td>EMUL</td><td>A<sup>0</sup> → e<sup>+</sup>e<sup>-</sup></td></tr><tr><td>24</td><td>FAISSNER</td><td>88</td><td>OSPK</td><td>Beam dump, A<sup>0</sup> → 2γ</td></tr><tr><td>25</td><td>BADIER</td><td>86</td><td>BDMP</td><td>A<sup>0</sup> → e<sup>+</sup>e<sup>-</sup></td></tr><tr><td>26</td><td>BERGSMA</td><td>85</td><td>CHRM</td><td>CERN beam dump</td></tr><tr><td>27</td><td>BERGSMA</td><td>85</td><td>CHRM</td><td>CERN beam dump</td></tr><tr><td>28</td><td>FAISSNER</td><td>72</td><td>OSPK</td><td>Beam dump, A<sup>0</sup> → 2γ</td></tr><tr><td>29</td><td>FRANK</td><td>83b</td><td>RVUE</td><td>LAMPF beam dump</td></tr><tr><td>30</td><td>HOFFMAN</td><td>83b</td><td>RVUE</td><td>LAMPF beam dump</td></tr><tr><td>31</td><td>FETSCHER</td><td>82</td><td>RVUE</td><td>See FAISSNER 81B</td></tr><tr><td>32</td><td>FAISSNER</td><td>81</td><td>OSPK</td><td>CERN PS ν wideband</td></tr><tr><td>33</td><td>FAISSNER</td><td>81b</td><td>OSPK</td><td>Beam dump, A<sup>0</sup> → 2γ</td></tr><tr><td>34</td><td>KIM</td><td>81</td><td>OSPK</td><td>26 GeV pN → A<sup>0</sup>X</td></tr><tr><td>35</td><td>FAISSNER</td><td>80</td><td>OSPK</td><td>Beam dump,</td></tr><tr><td></td><td></td><td></td><td>A<sup>0</sup> → e<sup>+</sup>e<sup>-</sup></td><td></td></tr><tr><td>&lt;2. &times; 10<sup>-11</sup></td><td>90</td><td>36</td><td>JACQUES</td><td>80 HLBC 28 GeV protons</td></tr><tr><td>&lt;1. &times; 10<sup>-13</sup></td><td>90</td><td>36</td><td>JACQUES</td><td>80 HLBC Beam dump</td></tr><tr><td></td><td></td><td>37</td><td>SOUKAS</td><td>80 CALO 28 GeV p beam dump</td></tr><tr><td></td><td></td><td>38</td><td>BECHIS</td><td>79 CNTR</td></tr><tr><td></td><td></td><td>39</td><td>COTEUS</td><td>79 OSPK Beam dump</td></tr><tr><td>&lt;1. &times; 10<sup>-8</sup></td><td>90</td><td>40</td><td>DISHAW</td><td>79 CALO 40 GeV p p</td></tr><tr><td>&lt;1. &times; 10<sup>-3</sup></td><td>95</td><td>40</td><td>ALIBRAN</td><td>78 HYBR Beam dump</td></tr><tr><td>&lt;6. &times; 10<sup>-9</sup></td><td>95</td><td>40</td><td>ASRATYAN</td><td>78b CALO Beam dump</td></tr><tr><td>&lt;1.5 &times; 10<sup>-8</sup></td><td>90</td><td>41</td><td>BELLOTTI</td><td>78 HLBC Beam dump</td></tr><tr><td>&lt;5.4 &times; 10<sup>-14</sup></td><td>90</td><td>41</td><td>BELLOTTI</td><td>78 HLBC m<sub>A<sup>0</sup></sub>=1.5 MeV</td></tr><tr><td>&lt;4.1 &times; 10<sup>-9</sup></td><td>90</td><td>41</td><td>BELLOTTI</td><td>78 HLBC m<sub>A<sup>0</sup></sub>=1 MeV</td></tr><tr><td>&lt;1. &times; 10<sup>-8</sup></td><td>90</td><td>42</td><td>BOSETTI</td><td>78b HYBR Beam dump</td></tr><tr><td>&lt;0.5 &times; 10<sup>-8</sup></td><td>90</td><td>43</td><td>DONNELLY</td><td>78 HANSL</td></tr><tr><td></td><td></td><td>44</td><td>MICELMAC...</td><td>78</td></tr><tr><td></td><td></td><td>45</td><td>VYSOTSKII</td><td>78</td></tr></tbody></table>

¹ ACCIARRI 23 search for axions in the NuMI neutrino beam target, which are produced through mixings with mesons due to the coupling with gluons, and exclude $f_{A^0}$ around tens of TeV for $m_{A^0} = 0.2-0.9$ GeV. They assume a slightly suppressed axion coupling to muons. See their Fig. 4 for the limits.

² BERTUZZO 23 employs an analysis analogous to ACCIARRI 23. They search for leptophilic axions primarily produced via $\tau \to \mu A^0$ and $\tau \to e A^0$, and exclude $f_{A^0}$ around $1 \times 10^6-6 \times 10^7$ GeV for $m_{A^0} = 0.2-1.7$ GeV. See their Fig. 2 for the limits.

³ AAD 22J set upper limits for the cross sections of $H \to A^0A^0 \to 4\mu$ and $H \to ZA^0 \to 2e2\mu$. See their Figs. 14 and 17 for the respective mass-dependent limits.

⁴ TUMASYAN 22AH set the limits of $O(10^{-6})$ with respect to the product of the branching fractions of $H \to A^0A^0$ and $A^0 \to e^+e^-$, $\mu^+\mu^-$ They also derive limits on the effective axion couplings contributing to $H \to A^0A^0$ and $H \to ZA^0$. See their Figs. 5 and 7 for the limits.

⁵ TUMASYAN 22R is analogous to GAVELA 20, and set a limit on the products of the axion couplings to gluons and Z bosons as $G_{AZZ} G_{Agg} < 6.64 \times 10^{-7} \text{ GeV}^{-2}$ at 95% CL for $f_{A^0} = 3$ TeV and $m_{A^0} < 100$ GeV. Here we use $c_{\tilde{G}} = G_{Agg} f_{A^0}/4$ and $c_Z = G_{AZZ} f_{A^0}/4$ to translate their limits. They also set a limit on the product of the axion couplings to gluons and ZH. See their Fig. 9 for the $f_{A^0}$-dependent limits.

⁶ AAD 21F look for axion production with an energetic jet and large missing $p_T$, and set a limit on the axion coupling to gluons, $c_{\tilde{G}}/f_{A^0} < 8 \times 10^{-6} \text{ GeV}^{-1}$ at 95% CL for $m_{A^0} = 1$ MeV. Using $c_{\tilde{G}} = \alpha_s/8\pi$, we interpret the limit as $f_{A^0} > 0.4$ TeV for $\alpha_s \approx 0.08$.

⁷ AAD 21K look for axion production with an energetic photon and large missing $p_T$, and set a limit on the axion coupling to a Z boson and photon, $G_{AZ\gamma} < 5.1 \times 10^{-4} \text{ GeV}^{-1}$ at 95% CL for $m_{A^0} = 1$ MeV and assuming $G_{A\gamma\gamma} = 0$.

⁸ AAD 21N look for axion production using the measurement of light-by-light scattering based on Pb+Pb collision data. They set the limit on the axion-photon coupling, $G_{A\gamma\gamma} < 5.3 \times 10^{-5}-3.4 \times 10^{-4} \text{ GeV}^{-1}$ at 95% CL for $m_{A^0} = 6-100$ GeV. Here we use $\Lambda_\gamma = G_{A\gamma\gamma}^{-1}$ to translate their limits. See their Fig. 9 for mass-dependent limits.

⁹ CARRA 21 is analogous to GAVELA 20, and they use the differential cross sections for WW and Zγ production measured with the ATLAS detector to set limits on the product of the axion couplings to gauge bosons as $G_{AWW} G_{Agg} < 6.2 \times 10^{-7} \text{ GeV}^{-2}$ and $G_{AZ\gamma} G_{Agg} < 3.7 \times 10^{-7} \text{ GeV}^{-2}$ at 95% CL for $m_{A^0} \lesssim 100$ GeV.

¹⁰ AAIJ 20AL look for a light new boson decaying into a pair of muons using the LHCb data with an integrated luminosity of 5.1 fb⁻¹, and set limits on the cross section over a range of $m_{X^0} = 0.22-3$ and 20-60 GeV. See Figs. 8 and 9 for mass-dependent limits.

¹¹ GAVELA 20 focus on the axion production as an s-channel off shell mediator, and use the Run 2 CMS public data to set limits on the product of the axion couplings to gluons and photons as well as Z bosons as $G_{A\gamma\gamma} G_{Agg} < 2.8 \times 10^{-7} \text{ GeV}^{-2}$ and $G_{AZZ} G_{Agg} < 9.8 \times 10^{-7} \text{ GeV}^{-2}$ for $m_{A^0} \lesssim 200$ GeV. See their Fig. 3 for the limits.

¹² SIRUNYAN 19BQ look for the pair production of a new light boson decaying into a pair of muons, and set limits on the product of the production cross section times branching fraction to dimuons squared times acceptance over a range of $m_{X^0} = 0.25-8.5$ GeV. See the right panel of their Fig. 1 for mass-dependent limits.

¹³ JAIN 07 claims evidence for $A^0 \to e^+e^-$ produced in $^{207}$Pb collision on nuclear emulsion (A<sub>g</sub>/Br) for $m(A^0) = 7 \pm 1$ or $19 \pm 1$ MeV and $\tau(A^0) \le 10^{-13}$ s.

¹⁴ AHMAD 97 reports a result of APEX Collaboration which studied positron production in $^{238}$U+232Ta and $^{238}$U+181Ta collisions, without requiring a coincident electron. No narrow lines were found for $250 < E_{e^+} < 750$ keV.

¹⁵ LEINBERGER 97 (ORANGE Collaboration) at GSI looked for a narrow sum-energy $e^+e^-$ line at $\sim 635$ keV in $^{238}$U+181Ta collision. Limits on the production probability for a narrow sum-energy $e^+e^-$ line are set. See their Table 2.

¹⁶ GANZ 96 (EPoS II Collaboration) has placed upper bounds on the production cross section of $e^+e^-$ pairs from $^{238}$U+181Ta and $^{238}$U+232Th collisions at GSI. See Table 2 for limits both for back-to-back and isotropic configurations of $e^+e^-$ pairs. These limit its rule out the existence of peaks in the $e^+e^-$ sum-energy distribution, reported by an earlier version of this experiment.

¹⁷ KAMEL 96 looked for $e^+e^-$ pairs from the collision of $^{32}$S (200 GeV/nucleon) and emulsion. No evidence of mass peaks is found in the region of sensitivity $m_{ee} > 2$ MeV.

¹⁸ BLUEMLEIN 92 is a proton beam dump experiment at Serpukhov with a secondary target to induce Bethe-Heitler production of $e^+e^-$ or $\mu^+\mu^-$ from the produce $A^0$. See Fig. 5 for the excluded region in $m_{A^0} \times$ plane. For the standard axion, $0.3 < x < 25$ is excluded at 95% CL. If combined with BLUEMLEIN 91, 0.008 < x < 32 is excluded.

¹⁹ MEIJERDREES 92 give $f(\pi^- p \to nA^0) B(A^0 \to e^+ e^-) / f(\pi^- p \to \text{all}) < 10^{-5}$ (90% CL) for $m_{A^0} = 100$ MeV, $\tau_{A^0} = 10^{-11}-10^{-23}$ sec. Limits ranging from $2.5 \times 10^{-3}$ to $10^{-7}$ are given for $m_{A^0} = 25-136$ MeV.

²⁰ BLUEMLEIN 91 is a proton beam dump experiment at Serpukhov. No candidate event for $A^0 \to e^+e^-$, $\gamma\gamma$ are found. Fig. 6 gives the excluded region in $m_{A^0} \times$ plane ($x = \tan\beta = v_2/v_1$). Standard axion is excluded for $0.2 < m_{A^0} < 3.2$ MeV for most $x > 1$, 0.2-11 MeV for most $x < 1$.

²¹ FAISSNER 89 searched for $A^0 \to e^+e^-$ in a proton beam dump experiment at SIN. No excess of events was observed over the background. A standard axion with mass $2m_{e-20}$ MeV is excluded. Lower limit on $f_{A^0}$ of $\approx 10^4$ GeV is excluded for $m_{A^0} = 2m_{e-20}$ MeV.

²² DEBOER 88 reanalyze EL-NADI 88 data and claim evidence for three distinct states with mass $\sim 1.1$, $\sim 2.1$, and $\sim 9$ MeV, lifetimes $10^{-16}-10^{-15}$ s decaying to $e^+e^-$ and note the similarity of the data with those of a cosmic-ray experiment by Bristol group (B.M. Anand, Proc. of the Royal Society of London, Section A A22 183 (1953)). For a criticism see PERKINS 89, who suggests that the events are compatible with $\pi^0$ Dalitz decay. DEBOER 89b is a reply which contests the criticism.

²³ EL-NADI 88 claim the existence of a neutral particle decaying into $e^+e^-$ with mass $1.60 \pm 0.59$ MeV, lifetime $(0.15 \pm 0.01) \times 10^{-14}$ s, which is produced in heavy ion interactions with emulsion nuclei at $\sim 4$ GeV/c/nucleon.

²⁴ FAISSNER 88 is a proton beam dump experiment at SIN. They found no candidate event for $A^0 \to \gamma\gamma$. A standard axion decaying to $2\gamma$ is excluded except for a region $x \simeq 1$. Lower limit on $f_{A^0}$ of $10^2-10^3$ GeV is given for $m_{A^0} = 0.1-1$ MeV.

²⁵ BADIER 86 did not find long-lived $A^0$ in 300 GeV $\pi^-$ Beam Dump Experiment that decays into $e^+e^-$ in the mass range $m_{A^0} = (20-200)$ MeV, which excludes the $A^0$ decay constant $f(A^0)$ in the interval $(60-600)$ GeV. See their figure 6 for excluded region on $f(A^0)-m_{A^0}$ plane.

²⁶ BERGSA 85 look for $A^0 \to 2\gamma$, $e^+e^-$, $\mu^+\mu^-$ First limit above is for $m_{A^0} = 1$ MeV; second is for 200 MeV. See their figure 4 for excluded region on $f_{A^0}-m_{A^0}$ plane,
where $f_{A^0}$ is $A^0$ decay constant. For Peccei-Quinn PECCEI 77 $A^0$, $m_{A^0} < 180$ keV and $\tau > 0.037$ s. (CL = 90%). For the axion of FAISSNER 81B at 250 keV, BERGSMA 85 expect 15 events but observe zero.

27 FAISSNER 83 observed 19 $1-\gamma$ and 12 $2-\gamma$ events where a background of 4.8 and 2.3 respectively is expected. A small-angle peak is observed even if iron wall is set in front of the decay region.

28 FAISSNER 83B extrapolate SIN $\gamma$ signal to LAMPF $\nu$ experimental condition. Resulting 37 $\gamma$'s are not at variance with LAMPF upper limit of 450 $\gamma$'s. Derived from LAMPF limit that $[d\sigma(A^0)/d\omega$ at 90]$^0$m$_{A^0}/\tau_{A^0} < 14 \times 10^{-35}$ cm$^2$ sr$^{-1}$ MeV ms$^{-1}$. See comment on FRANK 83B.

29 FRANK 83B stress the importance of LAMPF data bins with negative net signal. By statistical analysis say that LAMPF and SIN-A0 are at variance when extrapolation by phase-space model is done. They find LAMPF upper limit is 248 not 450 $\gamma$'s. See comment on FAISSNER 83B.

30 HOFFMAN 83 set CL = 90% limit $d\sigma/dt$ B($e^+e^-$) < 3.5 $\times 10^{-32}$ cm$^2$/GeV$^2$ for 140 $<m_{A^0} < 160$ MeV. Limit assumes $\tau(A^0) < 10^{-9}$ s.

31 FETSCHER 82 reanalyzes SIN beam-dump data of FAISSNER 81. Claims no evidence for axion since 2-$\gamma$ peak rate remarkably decreases if iron wall is set in front of the decay region.

32 FAISSNER 81 see excess $\mu$e events. Suggest axion interactions.

33 FAISSNER 81B is SIN 590 MeV proton beam dump. Observed 14.5 $\pm 5.0$ events of $2\gamma$ decay of long-lived neutral penetrating particle with $m_{2\gamma} \lesssim 1$ MeV. Axion interpretation with $\eta-A^0$ mixing gives $m_{A^0} = 250 \pm 25$ keV, $\tau_{(2\gamma)} = (7.3 \pm 3.7) \times 10^{-3}$ s from above rate. See critical remarks below in comments of FETSCHER 82, FAISSNER 83, FAISSNER 83B, FRANK 83B, and BERGSMA 85. Also see in the next subsection ALEK-SEEV 82B, CAVAIGNAC 83, and ANANEV 85.

34 KIM 81 analyzed 8 candidates for $A^0 \to 2\gamma$ obtained by Aachen-Padova experiment at CERN with 26 GeV protons on Be. Estimated axion mass is about 300 keV and lifetime is $(0.86 \sim 5.6) \times 10^{-3}$ s depending on models. Faisner (private communication), says axion production underestimated and mass overestimated. Correct value around 200 keV.

35 FAISSNER 80 is SIN beam dump experiment with 590 MeV protons looking for $A^0 \to e^+e^-$ decay. Assuming $A^0/\tau^0 = 5.5 \times 10^{-7}$, obtained decay rate limit 20/(A$^0$ mass) MeV/s (CL = 90%), which is about $10^{-7}$ below theory and interpreted as upper limit to $m_{A^0} < 2m_e$.

36 JACQUES 80 is a BNL beam dump experiment. First limit above comes from nonobservation of excess neutral-current-type events $[\sigma(production)\sigma(interaction) < 7. \times 10^{-68}$ cm$^4$, CL = 90%]. Second limit is from nonobservation of axion decays into $2\gamma$'s or $e^+e^-$, and for axion mass a few MeV.

37 SOUKAS 80 at BNL observed no excess of neutral-current-type events in beam dump.

38 BECHIS 79 looked for the axion production in low energy electron Bremsstrahlung and the subsequent decay into either $2\gamma$ or $e^+e^-$. No signal found. CL = 90% limits for model parameter(s) are given.

39 COTEUS 79 is a beam dump experiment at BNL.

40 DISHAW 79 is a calorimetric experiment and looks for low energy tail of energy distributions due to energy lost to weakly interacting particles.

41 BELLOTTI 78 first value comes from search for $A^0 \to e^+e^-$. Second value comes from search for $A^0 \to 2\gamma$, assuming mass $<2m_e$. For any mass satisfying this, limit is above value $\times (\text{mass}^{-4})$. Third value uses data of PL 60B 401 and quotes $\sigma(production)\sigma(interaction) < 10^{-67}$ cm$^4$.

42 BOSETTI 78b quotes $\sigma(production)\sigma(interaction) < 2. \times 10^{-67}$ cm$^4$.

43 DONNELLY 78 examines data from reactor neutrino experiments of REINES 76 and GURR 74 as well as SLAC beam dump experiment. Evidence is negative.

44 MICELMACHER 78 finds no evidence of axion existence in reactor experiments of REINES 76 and GURR 74. (See reference under DONNELLY 78 below).

45 VYSOTSKII 78 derived lower limit for the axion mass 25 keV from luminosity of the sun and 200 keV from red supergiants.

### A$^0$ (Axion) Searches in Reactor Experiments

<table><thead><tr><td>VALUE</td><td>DOCUMENT ID</td><td>TECN</td><td>COMMENT</td></tr></thead><tbody></tbody></table>

• • • We do not use the following data for averages, fits, limits, etc. • • •

1 CHANG 07 Primakoff or Compton

2 ALTMANN 95 CNTR Reactor; $A^0 \to e^+e^-$

3 KETOV 86 SPEC Reactor; $A^0 \to \gamma\gamma$

4 KOCH 86 SPEC Reactor; $A^0 \to \gamma\gamma$

5 DATAR 82 CNTR Light water reactor

6 VUILLEUMIER 81 CNTR Reactor; $A^0 \to 2\gamma$

1 CHANG 07 looked for monochromatic photons from Primakoff or Compton conversion of axions from the Kuo-Sheng reactor due to axion coupling to photon or electron, respectively. The search places model-independent limits on the products $G_{A\gamma\gamma}G_{ANN}$ and $G_{Aee}G_{ANN}$ for $m(A^0)$ less than the MeV range.

2 ALTMANN 95 looked for $A^0$ decaying into $e^+e^-$ from the Bugey 5 nuclear reactor. They obtain an upper limit on the $A^0$ production rate of $\omega(A^0)/\omega(\gamma) \times B(A^0) \to e^+e^- < 10^{-16}$ for $m_{A^0} = 1.5$ MeV at 90% CL. The limit is weaker for heavier $A^0$. In the case of a standard axion, this limit excludes a mass in the range $2m_e < m_{A^0} < 4.8$ MeV at 90% CL. See Fig. 5 of their paper for exclusion limits of axion-like resonances $Z^0$ in the $(m_{X^0}, f_{X^0})$ plane.

3 KETOV 86 searched for $A^0$ at the Rovno nuclear power plant. They found an upper limit on the $A^0$ production probability of 0.8 [100 keV/$m_{A^0}$] $\times 10^{-6}$ per fission. In the standard axion model, this corresponds to $m_{A^0} > 150$ keV. Not valid for $m_{A^0} \gtrsim 1$ MeV.

4 KOCH 86 searched for $A^0 \to \gamma\gamma$ at nuclear power reactor Biblis A. They found an upper limit on the $A^0$ production rate of $\omega(A^0)/\omega(\gamma(M1)) < 1.5 \times 10^{-10}$ (CL=95%). Standard axion with $m_{A^0} = 250$ keV gives $10^{-5}$ for the ratio. Not valid for $m_{A^0} > 1022$ keV.

5 DATAR 82 looked for $A^0 \to 2\gamma$ in neutron capture ($np \to dA^0$) at Tarapur 500 MW reactor. Sensitive to sum of $l=0$ and $l=1$ amplitudes. With ZEHNDER 81 ($l=1$) result, assert nonexistence of standard $A^0$.

6 VUILLEUMIER 81 is at Grenoble reactor. Set limit $m_{A^0} < 280$ keV.

### A$^0$ (Axion) and Other Light Boson ($X^0$) Searches in Nuclear Transitions

Limits are for branching ratio.

<table><thead><tr><th>VALUE</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>&lt; 8.89 &times; 10<sup>-6</sup></td><td>90</td><td>1 DERBIN</td><td>23</td><td>CNTR M1 transition of <sup>169</sup>Tm</td></tr><tr><td>&lt; 8.5 &times; 10<sup>-6</sup></td><td>90</td><td>2 DERBIN</td><td>02</td><td>CNTR <sup>125m</sup>Te decay</td></tr><tr><td>&lt; 5.5 &times; 10<sup>-10</sup></td><td>95</td><td>3 DEBOER</td><td>97c</td><td>RVUE M1 transitions</td></tr><tr><td>&lt; 1.2 &times; 10<sup>-6</sup></td><td>95</td><td>4 TSUNODA</td><td>95</td><td>CNTR <sup>252</sup>Cf fission, $A^0 \to ee$</td></tr><tr><td>&lt; 2 &times; 10<sup>-4</sup></td><td>90</td><td>5 MINOWA</td><td>93</td><td>CNTR <sup>139</sup>La* &rarr; <sup>139</sup>LaA<sup>0</sup></td></tr><tr><td>&lt; 1.5 &times; 10<sup>-9</sup></td><td>95</td><td>6 HICKS</td><td>92</td><td>CNTR <sup>35</sup>S decay, $A^0 \to \gamma\gamma$</td></tr><tr><td>&lt;(0.4-10) &times; 10<sup>-3</sup></td><td>95</td><td>7 ASANUMA</td><td>90</td><td>CNTR <sup>241</sup>Am decay</td></tr><tr><td>&lt;(0.2-1) &times; 10<sup>-3</sup></td><td>90</td><td>8 DEBOER</td><td>90</td><td>CNTR <sup>8</sup>Be* &rarr; <sup>8</sup>BeA<sup>0</sup>,<br/>X<sup>0</sup> &rarr; <sup>e</sup>+<sup>e</sup>-<br/>Cu<sup>*</sup> &rarr; CuA<sup>0</sup>($A^0 \to 2\gamma$)</td></tr><tr><td>&lt; 1.5 &times; 10<sup>-4</sup></td><td>90</td><td>10 AVIGNONE</td><td>88</td><td>CNTR $A^0 \to e^+e^-$<br/>Cu<sup>*</sup> &rarr; CuA<sup>0</sup>($A^0 \to 2\gamma$,<br/>$A^0 \to e^+e^-$, $A^0 \to \gamma e$, $A^0 Z \to \gamma Z$)</td></tr><tr><td>&lt; 5 &times; 10<sup>-3</sup></td><td>90</td><td>11 DATAR</td><td>88</td><td>CNTR <sup>12C*</sup> &rarr; <sup>12</sup>Ca<sup>0</sup></td></tr><tr><td>&lt; 3.4 &times; 10<sup>-5</sup></td><td>95</td><td>12 DEBOER</td><td>88c</td><td>CNTR <sup>16</sup>O* &rarr; <sup>16</sup>OX<sup>0</sup>,<br/>X<sup>0</sup> &rarr; <sup>e</sup>+<sup>e</sup>-<br/>2H<sup>+</sup>, $A^0 \to e^+e^-$</td></tr><tr><td>&lt; 4 &times; 10<sup>-4</sup></td><td>95</td><td>13 DOEHNER</td><td>88</td><td>SPEC Li<sup>+</sup> isovector decay</td></tr><tr><td>&lt; 3 &times; 10<sup>-3</sup></td><td>95</td><td>14 SAVAGE</td><td>88</td><td>CNTR Nuclear decay (isovector)</td></tr><tr><td>&lt;10.6 &times; 10<sup>-2</sup></td><td>90</td><td>14 SAVAGE</td><td>88</td><td>CNTR Nuclear decay (isoscalar)</td></tr><tr><td>&lt;10.8</td><td>90</td><td>15 HALLIN</td><td>86</td><td>SPEC <sup>6</sup>Li isovector decay</td></tr><tr><td>&lt; 2.2</td><td>90</td><td>15 HALLIN</td><td>86</td><td>SPEC <sup>10</sup>B isoscalar decays</td></tr><tr><td>&lt; 4 &times; 10<sup>-4</sup></td><td>90</td><td>15 HALLIN</td><td>86</td><td>SPEC <sup>14</sup>N isoscalar decays</td></tr><tr><td>&lt; 4 &times; 10<sup>-4</sup></td><td>90</td><td>16 SAVAGE</td><td>86b</td><td>CNTR <sup>14</sup>N*</td></tr><tr><td>&lt; 4 &times; 10<sup>-4</sup></td><td>90</td><td>17 ANANEV</td><td>85</td><td>CNTR Li<sup>+</sup>, deut* $A^0 \to 2\gamma$</td></tr><tr><td>&lt; 4 &times; 10<sup>-4</sup></td><td>90</td><td>18 CAVAIGNAC</td><td>83</td><td>CNTR <sup>97</sup>Nb<sup>*</sup>, deut* transition<br/>$A^0 \to 2\gamma$</td></tr><tr><td>&lt; 4 &times; 10<sup>-4</sup></td><td>90</td><td>19 ALEKSEEV</td><td>82b</td><td>CNTR Li<sup>+</sup>, deut* transition<br/>$A^0 \to 2\gamma$</td></tr><tr><td>&lt; 4 &times; 10<sup>-4</sup></td><td>90</td><td>20 LEHMANN</td><td>82</td><td>CNTR Cu<sup>*</sup> &rarr; CuA<sup>0</sup> ($A^0 \to 2\gamma$)</td></tr><tr><td>&lt; 4 &times; 10<sup>-4</sup></td><td>90</td><td>21 ZEHNDER</td><td>82</td><td>CNTR Li<sup>+</sup>, Nb<sup>*</sup> decay, n-capt.</td></tr><tr><td>&lt; 4 &times; 10<sup>-4</sup></td><td>90</td><td>22 ZEHNDER</td><td>81</td><td>CNTR Ba<sup>+</sup> &rarr; BaA<sup>0</sup> ($A^0 \to 2\gamma$)</td></tr><tr><td>&lt; 4 &times; 10<sup>-4</sup></td><td>90</td><td>23 CALAPRICE</td><td>79</td><td>Carbon</td></tr></tbody></table>

1 DERBIN 23 use a thallium garnet bolometric detector to search for the 8.4 keV solar axion line emitted from the M1 nuclear transition of <sup>169</sup>Tm. Their limits are equivalent to an upper bound on the KSVZ and DFSZ axion masses of 141 eV and 244 eV, respectively.

2 DERBIN 02 looked for the axion emission in an M1 transition in <sup>125m</sup>Te decay. They looked for a possible presence of a shifted energy spectrum in gamma rays due to the undetected axion.

3 DEBOER 97c reanalyzed the existent data on Nuclear M1 transitions and find that a 9 MeV boson decaying into $e^+e^-$ would explain the excess of events with large opening angles. See also DEBOER 01 for follow-up experiments.

4 TSUNODA 95 looked for axion emission when <sup>252</sup>Cf undergoes a spontaneous fission, with the axion decaying into $e^+e^-$. The bound is for $m_{A^0}=40$ MeV. It improves to $2.5 \times 10^{-5}$ for $m_{A^0}=200$ MeV.

5 MINOWA 93 studied chain process, <sup>139</sup>Ce &rarr; <sup>139</sup>La* by electron capture and M1 transition of <sup>139</sup>La* to the ground state. It does not assume decay modes of $A^0$. The bound applies for $m_{A^0} < 166$ keV.

6 HICKS 92 bound is applicable for $\tau_{X^0} < 4 \times 10^{-11}$ sec.

7 The ASANUMA 90 limit is for the branching fraction of $X^0$ emission per <sup>241</sup>Am$\alpha$ decay and valid for $\tau_{X^0} < 3 \times 10^{-11}$ s.

8 The DEBOER 90 limit is for the branching ratio <sup>8</sup>Be* (18.15 MeV, $1^+$) &rarr; <sup>8</sup>BeA$^0$, $A^0 \to e^+e^-$ for the mass range $m_{A^0} = 4-15$ MeV.

9 The BINI 89 limit is for the branching fraction of <sup>16</sup>O* (6.05 MeV, $0^+$) &rarr; <sup>16</sup>OX$^0$, $X^0 \to e^+e^-$ for $m_{X^0} = 1.5-3.1$ MeV. $\tau_{X^0} \lesssim 10^{-11}$ s is assumed. The spin-parity of X is restricted to $0^+$ or $1^-$.

10 AVIGNONE 88 looked for the <sup>1115</sup>KV transition C* &rarr; CuA$^0$, either from $A^0 \to 2\gamma$ in-flight decay or from the secondary $A^0$ interactions by Compton and by Primakoff processes. Limits for axion parameters are obtained for $m_{A^0} < 1.1$ MeV.

11 DATAR 88 rule out light pseudoscalar particle emission through its decay $A^0 \to e^+e^-$ in the mass range 1.02-2.5 MeV and lifetime range $10^{-13}-10^{-8}$ s. The above limit is for $\tau = 5 \times 10^{-13}$ s and $m = 1.7$ MeV; see the paper for the $\tau-m$ dependence of the limit.

12 The limit is for the branching fraction of <sup>16</sup>O* (6.05 MeV, $0^+$) &rarr; <sup>16</sup>OX$^0$, $X^0 \to e^+e^-$ against internal pair conversion for $m_{X^0} = 1.7$ MeV and $\tau_{X^0} < 10^{-11}$ s. Similar limits are obtained for $m_{X^0} = 1.3-3.2$ MeV. The spin parity of $X^0$ must be either $0^+$ or $1^-$. The limit at 1.7 MeV is translated into a limit for the $X^0$-nucleon coupling constant: $g^2_{X^0NN}/4\pi < 2.3 \times 10^{-9}$.

13 The DOEHNER 88 limit is for $m_{A^0} = 1.7$ MeV, $\tau(A^0) < 10^{-10}$ s. Limits less than $10^{-4}$ are obtained for $m_{A^0} = 1.2-2.2$ MeV.

14 SAVAGE 88 looked for $A^0$ that decays into $e^+e^-$ in the decay of the 9.17 MeV $J^P = 2^+$ state in <sup>14</sup>N, 17.64 MeV state $J^P = 1^+$ in <sup>8</sup>Be, and the 18.15 MeV state $J^P = 1^+$ in <sup>8</sup>Be. This experiment constrains the isovector coupling of $A^0$ to hadrons, if $m_{A^0}$
$= (1.1 \rightarrow 2.2)$ MeV and the isoscalar coupling of $A^0$ to hadrons, if $m_{A^0} = (1.1 \rightarrow 2.6)$ MeV. Both limits are valid only if $\tau(A^0) \lesssim 1 \times 10^{-11}$ s.

15 Limits are for $\Gamma(A^0(1.8 \text{ MeV}))/\Gamma(\pi M1)$; i.e., for 1.8 MeV axion emission normalized to the rate for internal emission of $e^+e^-$ pairs. Valid for $\tau_{A^0} < 2 \times 10^{-11}$s. $^6$Li isovector decay data strongly disfavor PECCEI 86 model I, whereas the $^{10}$B and $^{14}$N isoscalar decay data strongly reject PECCEI 86 model II and III.

16 SAVAGE 86 looked for $A^0$ that decays into $e^+e^-$ in the decay of the 9.17 MeV $J^P = 2^+$ state in $^{14}$N. Limit on the branching fraction is valid if $\tau_{A^0} \lesssim 1 \times 10^{-11}$s for $m_{A^0} = (1.1-1.7)$ MeV. This experiment constrains the iso-vector coupling of $A^0$ to hadrons.

17 ANANEV 85 with IBR-2 pulsed reactor exclude standard $A^0$ at CL = 95% masses below 470 keV (Li\* decay) and below $2m_e$ for deuteron\* decay.

18 CAVAIGNAC 83 at Bugey reactor exclude axion at any $m_{97\text{Nb}^+\text{decay}}$ and axion with $m_{A^0}$ between 275 and 288 keV (deuteron\* decay).

19 ALEKSEEV 82 with IBR-2 pulsed reactor exclude standard $A^0$ at CL = 95% mass-ranges $m_{A^0} < 400$ keV (Li\* decay) and 330 keV $< m_{A^0} < 2.2$ MeV. (deuteron\* decay).

20 LEHMANN 82 obtained $A^0 \rightarrow 2\gamma$ rate $< 6.2 \times 10^{-5}$s (CL = 95%) excluding $m_{A^0}$ between 100 and 1000 keV.

21 ZEHNDER 82 used Gosgen 2.8GW light-water reactor to check $A^0$ production. No $2\gamma$ peak in Li\*, Nb\* decay (both single p transition) nor in n capture (combined with previous Ba\* negative result) rules out standard $A^0$. Set limit $m_{A^0} < 60$ keV for any $A^0$.

22 ZEHNDER 81 looked for $Ba^* \rightarrow A^0Ba$ transition with $A^0 \rightarrow 2\gamma$. Obtained $2\gamma$ coincidence rate $< 2.2 \times 10^{-5}$s (CL = 95%) excluding $m_{A^0} > 160$ keV (or 200 keV depending on Higgs mixing). However, see BARROSO 81.

23 CALAPRICE 79 saw no axion emission from excited states of carbon. Sensitive to axion mass between 1 and 15 MeV.

### A$^0$ (Axion) Limits from Its Electron Coupling

Limits are for $\tau(A^0 \rightarrow e^+e^-)$.

<table><thead><tr><th>VALUE (s)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td rowspan="6">none 4 &times; 10<sup>-16</sup>-4.5 &times; 10<sup>-12</sup></td><td rowspan="6">90</td><td>1 ANDREEV</td><td>21</td><td>NA64 eN &rarr; eA<sup>0</sup>N (A<sup>0</sup> &rarr; invibles)</td></tr><tr><td>2 ANDREEV</td><td>21B</td><td>NA64 eN &rarr; eA<sup>0</sup>N (A<sup>0</sup> &rarr; e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>3 BROSS</td><td>91</td><td>BDMP eN &rarr; eA<sup>0</sup>N (A<sup>0</sup> &rarr; e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>4 GUO</td><td>90</td><td>BDMP eN &rarr; eA<sup>0</sup>N (A<sup>0</sup> &rarr; e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>5 BJORKEN</td><td>88</td><td>CALO A &rarr; e<sup>+</sup>e<sup>-</sup> or 2&gamma;</td></tr><tr><td>6 BLINOV</td><td>88</td><td>MD1 ee &rarr; eeA<sup>0</sup> (A<sup>0</sup> &rarr; e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td rowspan="3">none 1 &times; 10<sup>-14</sup>-1 &times; 10<sup>-10</sup></td><td rowspan="3">90</td><td>7 RIORDAN</td><td>87</td><td>BDMP eN &rarr; eA<sup>0</sup>N (A<sup>0</sup> &rarr; e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>8 BROWN</td><td>86</td><td>BDMP eN &rarr; eA<sup>0</sup>N (A<sup>0</sup> &rarr; e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>9 DAVIER</td><td>86</td><td>BDMP eN &rarr; eA<sup>0</sup>N (A<sup>0</sup> &rarr; e<sup>+</sup>e<sup>-</sup>)</td></tr><tr><td>none 3 &times; 10<sup>-13</sup>-1 &times; 10<sup>-7</sup></td><td>90</td><td>10 KONAKA</td><td>86</td><td>BDMP eN &rarr; eA<sup>0</sup>N (A<sup>0</sup> &rarr; e<sup>+</sup>e<sup>-</sup>)</td></tr></tbody></table>

1 ANDREEV 21 look for invisible decays of axions coupled to electrons, and set limits on $g_{Aee} < 4.6 \times 10^{-6} - 3.1 \times 10^{-3}$ for $m_{A^0} = 10^{-3} - 1$ GeV. This limits the axion contribution to the electron $g-2$ to an order of magnitude less than the current experimental uncertainty. See their Figs. 3 and 4 for mass-dependent limits.

2 ANDREEV 21B set limits on $g_{Aee}$ in the range of $6.3 \times 10^{-6} - 1.6 \times 10^{-3}$ for $m_{A^0} = 2-17$ MeV at 90% CL. This excludes $6.6 \times 10^{-5} < g_{Aee} < 1 \times 10^{-4}$ at $m_{A^0} = 16.7$ MeV corresponding to the ATOMKI anomaly. See their Fig. 2 for mass-dependent limits.

3 The listed BROSS 91 limit is for $m_{A^0} = 1.14$ MeV. $B(A^0 \rightarrow e^+e^-) = 1$ assumed. Excluded domain in the $\tau_{A^0} - m_{A^0}$ plane extends up to $m_{A^0} \approx 7$ MeV (see Fig. 5). Combining with electron $g-2$ constraint, axions coupling only to $e^+e^-$ ruled out for $m_{A^0} < 4.8$ MeV (90% CL).

4 GUO 90 use the same apparatus as BROWN 86 and improve the previous limit in the shorter lifetime region. Combined with $g-2$ constraint, axions coupling only to $e^+e^-$ are ruled out for $m_{A^0} < 2.7$ MeV (90% CL).

5 BJORKEN 88 reports limits on axion parameters ($f_A$, $m_A$, $\tau_A$) for $m_{A^0} < 200$ MeV from electron beam-dump experiment with production via Primakoff photoproduction, bremsstrahlung from electrons, and resonant annihilation of positrons on atomic electrons.

6 BLINOV 88 assume zero spin, $m = 1.8$ MeV and lifetime $< 5 \times 10^{-12}$s and find $\Gamma(A^0 \rightarrow \gamma\gamma)B(A^0 \rightarrow e^+e^-) < 2$ eV (CL=90%).

7 Assumes $A^0\gamma\gamma$ coupling is small and hence Primakoff production is small. Their figure 2 shows limits on axions for $m_{A^0} < 15$ MeV.

8 Uses electrons in hadronic showers from an incident 800 GeV proton beam. Limits for $m_{A^0} < 15$ MeV are shown in their figure 3.

9 $m_{A^0} = 1.8$ MeV assumed. The excluded domain in the $\tau_{A^0} - m_{A^0}$ plane extends up to $m_{A^0} \approx 14$ MeV, see their figure 4.

10 The limits are obtained from their figure 3. Also given is the limit on the $A^0\gamma\gamma - A^0e^+e^-$ coupling plane by assuming Primakoff production.

### Search for $A^0$ (Axion) Resonance in Bhabha Scattering

The limit is for $\Gamma(A^0)[B(A^0 \rightarrow e^+e^-)]^2$.

<table><thead><tr><th>VALUE (10<sup>-3</sup> eV)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>• • •</td><td>We do not use the following data for averages, fits, limits, etc.</td><td></td><td></td><td></td></tr><tr><td>&lt; 1.3</td><td>97</td><td>1 HALLIN</td><td>92</td><td>CNTR $m_{A^0} = 1.75-1.88$ MeV</td></tr><tr><td>none 0.0016-0.47</td><td>90</td><td>2 HENDERSON</td><td>92C</td><td>CNTR $m_{A^0} = 1.5-1.86$ MeV</td></tr><tr><td>&lt; 2.0</td><td>90</td><td>3 WU</td><td>92</td><td>CNTR $m_{A^0} = 1.56-1.86$ MeV</td></tr><tr><td>&lt; 0.013</td><td>95</td><td>TSERTOS</td><td>91</td><td>CNTR $m_{A^0} = 1.832$ MeV</td></tr><tr><td>none 0.19-3.3</td><td>95</td><td>4 WIDMANN</td><td>91</td><td>CNTR $m_{A^0} = 1.78-1.92$ MeV</td></tr><tr><td>&lt; 5</td><td>97</td><td>BAUER</td><td>90</td><td>CNTR $m_{A^0} = 1.832$ MeV</td></tr><tr><td>none 0.09-1.5</td><td>95</td><td>5 JUDGE</td><td>90</td><td>CNTR $m_{A^0} = 1.832$ MeV, elastic</td></tr><tr><td>&lt; 1.9</td><td>97</td><td>6 TSERTOS</td><td>89</td><td>CNTR $m_{A^0} = 1.82$ MeV</td></tr><tr><td>&lt;(10-40)</td><td>97</td><td>6 TSERTOS</td><td>89</td><td>CNTR $m_{A^0} = 1.51-1.65$ MeV</td></tr><tr><td>&lt;(1-2.5)</td><td>97</td><td>6 TSERTOS</td><td>89</td><td>CNTR $m_{A^0} = 1.80-1.86$ MeV</td></tr><tr><td>&lt; 31</td><td>95</td><td>LORENZ</td><td>88</td><td>CNTR $m_{A^0} = 1.646$ MeV</td></tr><tr><td>&lt; 94</td><td>95</td><td>LORENZ</td><td>88</td><td>CNTR $m_{A^0} = 1.726$ MeV</td></tr><tr><td>&lt; 23</td><td>95</td><td>LORENZ</td><td>88</td><td>CNTR $m_{A^0} = 1.782$ MeV</td></tr><tr><td>&lt; 19</td><td>95</td><td>LORENZ</td><td>88</td><td>CNTR $m_{A^0} = 1.837$ MeV</td></tr><tr><td>&lt; 3.8</td><td>97</td><td>7 TSERTOS</td><td>88</td><td>CNTR $m_{A^0} = 1.832$ MeV</td></tr><tr><td rowspan="4">&lt;2500</td><td rowspan="4">90</td><td>8 VANKLINKEN</td><td>88</td><td>CNTR</td></tr><tr><td>9 MAIER</td><td>87</td><td>CNTR</td></tr><tr><td>MILLS</td><td>87</td><td>CNTR</td></tr><tr><td>10 VONWIMMER.B7</td><td>88</td><td>CNTR $m_{A^0} = 1.8$ MeV</td></tr></tbody></table>

1 HALLIN 92 quote limits on lifetime, $8 \times 10^{-14} - 5 \times 10^{-13}$ sec depending on mass, assuming $B(A^0 \rightarrow e^+e^-) = 100\%$. They say that TSERTOS 91 overstated their sensitivity by a factor of 3.

2 HENDERSON 92c exclude axion with lifetime $\tau_{A^0} = 1.4 \times 10^{-12} - 4.0 \times 10^{-10}$ s, assuming $B(A^0 \rightarrow e^+e^-) = 100\%$. HENDERSON 92c also exclude a vector boson with $\tau = 1.4 \times 10^{-12} - 6.0 \times 10^{-10}$ s.

3 WU 92 quote limits on lifetime $> 3.3 \times 10^{-13}$ s assuming $B(A^0 \rightarrow e^+e^-) = 100\%$. They say that TSERTOS 89 overestimate the limit by a factor of $\pi/2$. WU 92 also quote a bound for vector boson, $\tau > 8.2 \times 10^{-13}$ s.

4 WIDMANN 91 bound applies exclusively to the case $B(A^0 \rightarrow e^+e^-) = 1$, since the detection efficiency varies substantially as $\Gamma(A^0)_{\text{total}}$ changes. See their Fig. 6.

5 JUDGE 90 excludes an elastic pseudoscalar $e^+e^-$ resonance for $4.5 \times 10^{-13}$ s $< \tau(A^0) < 7.5 \times 10^{-12}$ s (95% CL) at $m_{A^0} = 1.832$ MeV. Comparable limits can be set for $m_{A^0} = 1.776-1.856$ MeV.

6 See also TSERTOS 88b in references.

7 The upper limit listed in TSERTOS 88 is too large by a factor of 4. See TSERTOS 88b, footnote 3.

8 VANKLINKEN 88 looked for relatively long-lived resonance ($\tau = 10^{-10}-10^{-12}$ s). The sensitivity is not sufficient to exclude such a narrow resonance.

9 MAIER 87 obtained limits $\Gamma \lesssim 60$ eV (100 eV) at $m_{A^0} \approx 1.64$ MeV (1.83 MeV) for energy resolution $\Delta E_{cm} \approx 3$ keV, where R is the resonance cross section normalized to that of Bhabha scattering, and $\Gamma = \Gamma^2 e e / \Gamma_{\text{total}}$. For a discussion implying that $\Delta E_{cm} \approx 10$ keV, see TSERTOS 89.

10 VONWIMMERSPERG 87 measured Bhabha scattering for $E_{cm} = 1.37-1.86$ MeV and found a possible peak at 1.73 with $\int \sigma dE_{cm} = 14.5 \pm 6.8$ keVb. For a comment and a reply, see VANKLINKEN 88b and VONWIMMERSPERG 88. Also see CONNELL 88.

### Search for $A^0$ (Axion) Resonance in $e^+e^- \rightarrow \gamma\gamma$

The limit is for $\Gamma(A^0 \rightarrow e^+e^-)\Gamma(A^0 \rightarrow \gamma\gamma) / \Gamma_{\text{total}}$.

<table><thead><tr><th>VALUE (10<sup>-3</sup> eV)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>• • •</td><td>We do not use the following data for averages, fits, limits, etc.</td><td></td><td></td><td></td></tr><tr><td>&lt; 0.18</td><td>95</td><td>VO</td><td>94</td><td>CNTR $m_{A^0} = 1.1$ MeV</td></tr><tr><td>&lt; 1.5</td><td>95</td><td>VO</td><td>94</td><td>CNTR $m_{A^0} = 1.4$ MeV</td></tr><tr><td>&lt;12</td><td>95</td><td>VO</td><td>94</td><td>CNTR $m_{A^0} = 1.7$ MeV</td></tr><tr><td>&lt; 6.6</td><td>95</td><td>1 TRZASKA</td><td>91</td><td>CNTR $m_{A^0} = 1.8$ MeV</td></tr><tr><td>&lt; 4.4</td><td>95</td><td>WIDMANN</td><td>91</td><td>CNTR $m_{A^0} = 1.78-1.92$ MeV</td></tr><tr><td rowspan="3">&lt; 0.11</td><td rowspan="3">95</td><td>2 FOX</td><td>89</td><td>CNTR</td></tr><tr><td>3 MINOWA</td><td>89</td><td>CNTR $m_{A^0} = 1.062$ MeV</td></tr><tr><td>CONNELL</td><td>88</td><td>CNTR $m_{A^0} = 1.580$ MeV</td></tr><tr><td>&lt;33</td><td>97</td><td>CONNELL</td><td>88</td><td>CNTR $m_{A^0} = 1.642$ MeV</td></tr><tr><td>&lt;42</td><td>97</td><td>CONNELL</td><td>88</td><td>CNTR $m_{A^0} = 1.782$ MeV</td></tr><tr><td>&lt;73</td><td>97</td><td>CONNELL</td><td>88</td><td>CNTR $m_{A^0} = 1.832$ MeV</td></tr><tr><td>&lt;79</td><td>97</td><td>CONNELL</td><td>88</td><td>CNTR $m_{A^0} = 1.832$ MeV</td></tr></tbody></table>

1 TRZASKA 91 also give limits in the range $(6.6-30) \times 10^{-3}$ eV (95% CL) for $m_{A^0} = 1.6-2.0$ MeV.

2 FOX 89 measured positron annihilation with an electron in the source material into two photons and found no signal at 1.062 MeV ($< 9 \times 10^{-5}$ of two-photon annihilation at rest).

3 Similar limits are obtained for $m_{A^0} = 1.045-1.085$ MeV.

### Search for $X^0$ (Light Boson) Resonance in $e^+e^- \rightarrow \gamma\gamma\gamma$

The limit is for $\Gamma(X^0 \rightarrow e^+e^-)\Gamma(X^0 \rightarrow \gamma\gamma\gamma) / \Gamma_{\text{total}}$. C invariance forbids spin-0 $X^0$ coupling to both $e^+e^-$ and $\gamma\gamma\gamma$.

<table><thead><tr><th>VALUE (10<sup>-3</sup> eV)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>• • •</td><td>We do not use the following data for averages, fits, limits, etc.</td><td></td><td></td><td></td></tr><tr><td>&lt; 0.2</td><td>95</td><td>1 VO</td><td>94</td><td>CNTR $m_{X^0} = 1.1-1.9$ MeV</td></tr><tr><td>&lt; 1.0</td><td>95</td><td>2 VO</td><td>94</td><td>CNTR $m_{X^0} = 1.1$ MeV</td></tr></tbody></table>
# Gauge & Higgs Boson Particle Listings
## Axions ($A^0$) and Other Very Light Bosons

<table><tr><td>&lt; 2.5</td><td>95</td><td>2 VO</td><td>94</td><td>CNTR $m_{X0}=1.4$ MeV</td></tr><tr><td>&lt;120</td><td>95</td><td>2 VO</td><td>94</td><td>CNTR $m_{X0}=1.7$ MeV</td></tr><tr><td>&lt; 3.8</td><td>95</td><td>3 SKALSEY</td><td>92</td><td>CNTR $m_{X0}=1.5$ MeV</td></tr></table>

¹ VO 94 looked for $X^0 \to \gamma\gamma\gamma$ decaying at rest. The precise limits depend on $m_{X0}$. See Fig. 2(b) in paper.

² VO 94 looked for $X^0 \to \gamma\gamma\gamma$ decaying in flight.

³ SKALSEY 92 also give limits 4.3 for $m_{X0} = 1.54$ and 7.5 for 1.64 MeV. The spin of $X^0$ is assumed to be one.

## Light Boson ($X^0$) Search in Nonresonant $e^+e^-$ Annihilation at Rest

Limits are for the ratio of $n\gamma + X^0$ production relative to $\gamma\gamma$.

<table><thead><tr><th>VALUE (units 10<sup>-6</sup>)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>&lt; 4.2</td><td>90</td><td>1 MITSUI</td><td>96</td><td>CNTR $\gamma$X<sup>0</sup></td></tr><tr><td>&lt; 4</td><td>68</td><td>2 SKALSEY</td><td>95</td><td>CNTR $\gamma$X<sup>0</sup></td></tr><tr><td>&lt;40</td><td>68</td><td>3 SKALSEY</td><td>95</td><td>RVUE $\gamma$X<sup>0</sup></td></tr><tr><td>&lt; 0.18</td><td>90</td><td>4 ADACHI</td><td>94</td><td>CNTR $\gamma\gamma$X<sup>0</sup>, X<sup>0</sup> $\to \gamma\gamma$</td></tr><tr><td>&lt; 0.26</td><td>90</td><td>5 ADACHI</td><td>94</td><td>CNTR $\gamma\gamma$X<sup>0</sup>, X<sup>0</sup> $\to \gamma\gamma$</td></tr><tr><td>&lt; 0.33</td><td>90</td><td>6 ADACHI</td><td>94</td><td>CNTR $\gamma$X<sup>0</sup>, X<sup>0</sup> $\to \gamma\gamma\gamma$</td></tr></tbody></table>

¹ MITSUI 96 looked for a monochromatic $\gamma$. The bound applies for a vector $X^0$ with $C=-1$ and $m_{X0} < 200$ keV. They derive an upper bound on $e e X^0$ coupling and hence on the branching ratio $B(\alpha\text{-Ps} \to \gamma\gamma X^0) < 6.2 \times 10^{-6}$. The bounds weaken for heavier $X^0$.

² SKALSEY 95 looked for a monochromatic $\gamma$ without an accompanying $\gamma$ in $e^+e^-$ annihilation. The bound applies for scalar and vector $X^0$ with $C = -1$ and $m_{X0} = 100-1000$ keV.

³ SKALSEY 95 reinterpreted the bound on $\gamma A^0$ decay of $\alpha$-Ps by ASAI 91 where 3% of delayed annihilations are not from $^{35}_{31}\text{S}$ states. The bound applies for scalar and vector $X^0$ with $C = -1$ and $m_{X0} = 0-800$ keV.

⁴ ADACHI 94 looked for a peak in the $\gamma\gamma$ invariant mass distribution in $\gamma\gamma\gamma$ production from $e^+e^-$ annihilation. The bound applies for $m_{X0} = 70-800$ keV.

⁵ ADACHI 94 looked for a peak in the missing-mass distribution in $\gamma\gamma$ channel, using $\gamma\gamma\gamma$ production from $e^+e^-$ annihilation. The bound applies for $m_{X0} < 800$ keV.

⁶ ADACHI 94 looked for a peak in the missing mass distribution in $\gamma\gamma\gamma$ channel, using $\gamma\gamma\gamma$ production from $e^+e^-$ annihilation. The bound applies for $m_{X0} = 200-900$ keV.

## Searches for Goldstone Bosons ($X^0$)

(Including Horizontal Bosons and Majorons.) Limits are for branching ratios.

<table><thead><tr><th>VALUE</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>&lt;4.3 × 10<sup>-6</sup></td><td>90</td><td>1 ADACHI</td><td>23A BEL2</td><td>$\tau^− \to e^−X^0$, Familon</td></tr><tr><td>&lt;5.2 × 10<sup>-8</sup></td><td>90</td><td>2 ADACHI</td><td>23A BEL2</td><td>$\tau^− \to \mu^−X^0$, Familon</td></tr><tr><td>&lt;9 × 10<sup>-6</sup></td><td>90</td><td>3 FIORILLO</td><td>23 ASTR</td><td>Majoron, SN 1987A</td></tr><tr><td>&lt;7 × 10<sup>-12</sup></td><td>90</td><td>4 SANDNER</td><td>23 COSM</td><td>Majoron, CMB</td></tr><tr><td>&lt;9 × 10<sup>-6</sup></td><td>90</td><td>5 COLOMA</td><td>22A BORX</td><td>$\nu e$ non-standard interactions</td></tr><tr><td>&lt;3.3 × 10<sup>-2</sup></td><td>95</td><td>6 AGUILAR-AR...</td><td>21A PIEN</td><td>$\pi^− \to \mu^+X^0$, Majoron</td></tr><tr><td>&lt;1.8 × 10<sup>-2</sup></td><td>95</td><td>7 AGUILAR-AR...</td><td>21A PIEN</td><td>$\pi^− \to e^+X^0$, Majoron</td></tr><tr><td>&lt;6.4 × 10<sup>-9</sup></td><td>90</td><td>8 AGUILAR-AR...</td><td>21A PIEN</td><td>$\mu^+ \to e^+X^0$, Familon</td></tr><tr><td>&lt;1.4 × 10<sup>-5</sup></td><td>90</td><td>9 BALDINI</td><td>20 MEG</td><td>$\mu^+ \to e^+X^0$ ($X^0 \to \gamma\gamma$), Familon</td></tr><tr><td>&lt;1.1 × 10<sup>-9</sup></td><td>90</td><td>10 BAYES</td><td>15 TWST</td><td>$\mu^+ \to e^+X^0$, Familon</td></tr><tr><td>&lt;5 × 10<sup>-6</sup></td><td>90</td><td>11 LATTANZI</td><td>13 COSM</td><td>Majoron dark matter decay</td></tr><tr><td>&lt;1.3 × 10<sup>-9</sup></td><td>90</td><td>12 LESSA</td><td>07 RVUE</td><td>Meon, $\ell$ decays to Majoron</td></tr><tr><td>&lt;3 × 10<sup>-4</sup></td><td>90</td><td>13 FARZAN</td><td>03 ASTR</td><td>Majoron, SN cooling</td></tr><tr><td>&lt;1 × 10<sup>-10</sup></td><td>90</td><td>14 DIAZ</td><td>98 THEO</td><td>$H^0 \to X^0X^0$, $A^0 \to X^0X^0$, Majoron</td></tr><tr><td>&lt;2.6 × 10<sup>-6</sup></td><td>90</td><td>15 BOBRAKOV</td><td>91</td><td>Electron quasi-magnetic interaction</td></tr><tr><td>&lt;1.8 × 10<sup>-2</sup></td><td>95</td><td>16 ALBRECHT</td><td>90E ARG</td><td>$\tau^− \to \mu^+X^0$, Familon</td></tr><tr><td>&lt;6.4 × 10<sup>-9</sup></td><td>90</td><td>16 ALBRECHT</td><td>90E ARG</td><td>$\tau^− \to e^+X^0$, Familon</td></tr><tr><td>&lt;1.4 × 10<sup>-5</sup></td><td>90</td><td>17 ATIYA</td><td>90 B787</td><td>$K^+ \to \pi^+X^0$, Familon</td></tr><tr><td>&lt;1.1 × 10<sup>-9</sup></td><td>90</td><td>18 BALKE</td><td>88 CNTR</td><td>$\mu^+ \to e^+X^0$, Familon</td></tr><tr><td>&lt;5 × 10<sup>-6</sup></td><td>90</td><td>19 BOLTON</td><td>88 CBOX</td><td>$\mu^+ \to e^+\gamma X^0$. Familon</td></tr><tr><td>&lt;1.3 × 10<sup>-9</sup></td><td>90</td><td>20 CHANDA</td><td>88 ASTR</td><td>Sun, Majoron</td></tr><tr><td>&lt;3 × 10<sup>-4</sup></td><td>90</td><td>21 CHOI</td><td>88 ASTR</td><td>Majoron, SN 1987A</td></tr><tr><td>&lt;1 × 10<sup>-10</sup></td><td>90</td><td>22 PICCIOTTO</td><td>88 CNTR</td><td>$\pi^− \to e^+X^0$, Majoron</td></tr><tr><td>&lt;1.4 × 10<sup>-5</sup></td><td>90</td><td>23 GOLDMAN</td><td>87 CNTR</td><td>$\mu^− \to e^+\gamma X^0$. Familon</td></tr><tr><td>&lt;1 × 10<sup>-10</sup></td><td>90</td><td>24 BRYMAN</td><td>86B RVUE</td><td>$\mu^− \to e^+X^0$, Familon</td></tr><tr><td>&lt;2.6 × 10<sup>-6</sup></td><td>90</td><td>25 EICHLER</td><td>86 SPEC</td><td>$\mu^+ \to e^+X^0$. Familon</td></tr><tr><td>&lt;1 × 10<sup>-10</sup></td><td>90</td><td>26 JODIDIO</td><td>86 SPEC</td><td>$\mu^+ \to e^+X^0$. Familon</td></tr><tr><td>&lt;2.6 × 10<sup>-6</sup></td><td>90</td><td>27 BALTRUSAIT...</td><td>85 MRK3</td><td>$\tau^− \to \ell^+X^0$. Familon</td></tr><tr><td>&lt;1 × 10<sup>-10</sup></td><td>90</td><td>28 DICUS</td><td>83 COSM</td><td>$\nu(\text{hvy}) \to \nu(\text{light})X^0$</td></tr></tbody></table>

¹ ADACHI 23A set limits in the range of $1.1 \times 10^{-3} - 9.7 \times 10^{-3}$ for $0 < m_{X0} < 1.6$ GeV on $B(\tau^− \to e^−X^0)/B(\tau^− \to e^−\tau_\nu\tau_\nu)$. See their Fig. 2 for mass-dependent limits.

² ADACHI 23A set limits in the range of $7 \times 10^{-4} - 1.22 \times 10^{-2}$ for $0 < m_{X0} < 1.6$ GeV on $B(\tau^− \to e^−X^0)/B(\tau^− \to \mu^−\tau_\mu\nu\tau_\nu)$. See their Fig. 2 for mass-dependent limits.

³ FIORILLO 23 used data from Kamiokande-II and IMB on the neutrino flux from SN1987A to constrain the universal neutrino Majoron Yukawa coupling, $g$. They set an upper limit of $g m_{X0} \lesssim 10^{-9}$ MeV for Majoron masses 100 eV $\lesssim m_{X0} \lesssim 100$ MeV, using neutrino coalescence as production of Majorons which then decay back to neutrinos. See their Fig. 1 for the mass-dependent limits.

⁴ SANDNER 23 study Majoron production via neutrino inverse decay and use Planck data to constrain the neutrino Majoron Yukawa coupling to $g \lesssim 2 \times 10^{-13} - 1 \times 10^{-12}$ for Majoron masses $m_{X0} = 1-10$ eV. See their Fig. 1 for mass-dependent limits.

⁵ COLOMA 22A used the spectral data of Borexino Phase II to constrain the neutrino non-standard interaction with electrons mediated by a scalar or a pseudoscalar. Limits on the universal coupling to neutrinos and electrons between $2 \times 10^{-6}$ and $10^{-4}$ are obtained for $m_{X0} \lesssim 30-40$ MeV. See their Fig. 6 for mass-dependent limits.

⁶ AGUILAR-AREVALO 21A quoted limit applies to $m_{X0} = 33.9$ MeV. Limits between $4.3 \times 10^{-6}$ and $7.5 \times 10^{-5}$ are obtained for $0 < m_{X0} < 33.9$ MeV. The lifetime of $X^0$ is assumed to be long enough. See their Fig. 6 for mass-dependent limits.

⁷ AGUILAR-AREVALO 21A quoted limit applies to $m_{X0} = 85$ MeV. Limits between $5.2 \times 10^{-8}$ and $1.4 \times 10^{-6}$ are obtained for $0 < m_{X0} < 120$ MeV, which improve the limits of PICCIOTTO 88 by an order of magnitude. The lifetime of $X^0$ is assumed to be long enough. See their Fig. 4 for mass-dependent limits.

⁸ AGUILAR-AREVALO 20 obtained limits of order $10^{-5}$ for $m_{X0} = 47.8-95.1$ MeV. The quoted limit applies to $m_{X0} = 75$ MeV. See their Fig. 1 for mass-dependent limits.

⁹ BALDINI 20 obtained limits for $m_{X0} = 20-45$ MeV and $\tau_{X0} < 40$ ps, and supersedes BOLTON 88 for $m_{X0} = 20-40$ MeV. See their Fig. 17 for mass-dependent limits.

¹⁰ BAYES 15 limits are the average over $m_{X0} = 13-80$ MeV for the isotropic decay distribution of positrons. See their Fig. 4 and Table II for the mass-dependent limits as well as the dependence on the decay anisotropy. In particular, they find a limit $< 58 \times 10^{-6}$ at 90% CL for massless familiars and for the same asymmetry as normal muon decay, a case not covered by JODIDIO 86.

¹¹ LATTANZI 13 use WMAP 9 year data as well as X-ray and $\gamma$-ray observations to derive limits on decaying majoron dark matter. A limit on the decay width $\Gamma(X^0 \to \nu\bar{\nu}) < 6.4 \times 10^{-19} \text{ s}^{-1}$ at 95% CL is found if majorons make up all of the dark matter.

¹² LESSA 07 consider decays of the form Meson $\to \ell\nu$ Majoron and $\ell \to \ell'\nu\bar{\nu}$ Majoron and use existing data to derive limits on the neutrino-Majoron Yukawa couplings $g_{\alpha\beta}$ ($\alpha, \beta = e, \mu, \tau$). Their best limits are $|g_{e\alpha}|^2 < 5.5 \times 10^{-6}$, $|g_{\mu\alpha}|^2 < 4.5 \times 10^{-5}$, $|g_{\tau\alpha}|^2 < 5.5 \times 10^{-2}$ at CL = 90%.

¹³ FARZAN 03 set limits on the neutrino Majoron Yukawa coupling, $|g_{ee}|^2 < 4 \times 10^{-7}$, by considering the SN cooling due to the massless Majoron emission via neutrino coalescence. They also exclude values around $10^{-5}$ for both $g_{e\mu}$ and $g_{\mu\mu}$ using the process $\nu\nu \to X^0X^0$.

¹⁴ DIAZ 98 studied models of spontaneously broken lepton number with both singlet and triplet Higgses. They obtain limits on the parameter space from invisible decay $Z \to H^0A^0$ and $H^0 \to X^0X^0$.

¹⁵ BOBRAKOV 91 searched for anomalous magnetic interactions between polarized electrons expected from the exchange of a massless pseudoscalar boson (arion). A limit $x_e^2 < 2 \times 10^{-4}$ (95%CL) is found for the effective anomalous magneton parametrized as $x_e(G_F/8\pi\sqrt{2})^{1/2}$.

¹⁶ ALBRECHT 90E limits are for $B(\tau \to \ell^+X^0)/B(\tau \to \ell\nu\bar{\nu})$. Valid for $m_{X0} < 100$ MeV. The limits rise to 7.1% (for $\mu$), 5.0% (for $e$) for $m_{X0} = 500$ MeV.

¹⁷ ATIYA 90 limit is for $m_{X0} = 0$. The limit $B < 1 \times 10^{-8}$ holds for $m_{X0} < 95$ MeV. For the reduction of the limit due to finite lifetime of $X^0$, see their Fig. 3.

¹⁸ BALKE 88 limits are for $B(\mu^+ \to e^+X^0)$. Valid for $m_{X0} < 80$ MeV and $\tau_{X0} > 10^{-8}$ sec.

¹⁹ BOLTON 88 limit corresponds to $F > 3.1 \times 10^9$ GeV, which does not depend on the chirality property of the coupling.

²⁰ CHANDA 88 find $v_T < 10$ MeV for the weak-triplet Higgs vacuum expectation value in Gelmini-Roncadelli model, and $v_S > 5.8 \times 10^6$ GeV in the singlet Majoron model.

²¹ CHOI 88 used the observed neutrino flux from the supernova SN 1987A to exclude the neutrino Majoron Yukawa coupling $h$ in the range $2 \times 10^{-5} < h < 3 \times 10^{-4}$ for the interaction $L_{\text{int}} = \frac{1}{2} \hbar \bar{\psi} \gamma^\mu \psi \gamma_\nu \psi \phi \chi$. For several families of neutrinos, the limit applies for $(\Sigma h_j^2)^{1/4}$.

²² PICCIOTTO 88 limit applies when $m_{X0} < 55$ MeV and $\tau_{X0} > 2\text{ns}$, and it decreases to $4 \times 10^{-7}$ at $m_{X0} = 125$ MeV, beyond which no limit is obtained.

²³ GOLDMAN 87 limit corresponds to $F > 2.9 \times 10^9$ GeV for the family symmetry breaking scale from the Lagrangian $L_{\text{int}} = (1/F)\bar{\psi}\mu^\mu(a+b\gamma_5)\psi e^0\partial_\mu\phi X^0$ with $a^2+b^2=1$. This is not as sensitive as the limit $F > 9.9 \times 10^9$ GeV derived from the search for $\mu^+ \to e^+X^0$ by JODIDIO 86, but does not depend on the chirality property of the coupling.

²⁴ Limits are for $\Gamma(\mu \to e^+X^0)/\Gamma(\mu \to e\nu\bar{\nu})$. Valid when $m_{X0} = 0-93.4$, 98.1-103.5 MeV.

²⁵ EICHLER 86 looked for $\mu^+ \to e^+X^0$ followed by $X^0 \to e^+e^-$. Limits on the branching fraction depend on the mass and lifetime of $X^0$. The quoted limits are valid when $\tau_{X0} \lesssim 3 \times 10^{-10}$ s if the decays are kinematically allowed.

²⁶ JODIDIO 86 corresponds to $F > 9.9 \times 10^9$ GeV for the family symmetry breaking scale with the parity-conserving effective Lagrangian $L_{\text{int}} = (1/F) \bar{\psi}\mu^\mu \psi e^0 \partial_\mu \phi X^0$.

²⁷ BALTRUSAITIS 85 search for light Goldstone boson($X^0$) of broken U(1). CL = 95% limits are $B(\tau \to \mu^+X^0)/B(\tau \to \mu^+\nu\nu) < 0.125$ and $B(\tau \to e^+X^0)/B(\tau \to e^+\nu\nu) < 0.04$. Inferred limit for the symmetry breaking scale is $m > 3000$ TeV.

²⁸ The primordial heavy neutrino must decay into $\nu$ and familon, $f_A$, early so that the red-shifted decay products are below critical density, see their table. In addition, $K \to \pi f_A$ and $\mu \to e f_A$ are unseen. Combining these excludes $m_{\text{heavily}}$ between $5 \times 10^{-5}$ and $5 \times 10^{-4}$ MeV ($\mu$ decay) and $m_{\text{heavily}}$ between $5 \times 10^{-5}$ and $0.1$ MeV ($K$-decay).
## Majoron Searches in Neutrinoless Double β Decay

Limits are for the half-life of neutrinoless ββ decay with a Majoron emission.

No experiment currently claims any such evidence. Only the best or comparable limits for each isotope are reported.

<table><thead><tr><th>1/2(10<sup>21</sup> yr)</th><th>CL% ISOTOPE</th><th>TRANSITION</th><th>METHOD</th><th>DOCUMENT ID</th></tr></thead><tbody><tr><td>&gt;T200</td><td>90</td><td><sup>128</sup>Te</td><td>CNTR</td><td>1 BERNATOW... 92</td></tr></tbody></table><p>• • • We do not use the following data for averages, fits, limits, etc. • • •</p><table><tbody><tr><td>&gt; 120</td><td>90</td><td>82Se</td><td>0ν1χ</td><td>CUPID-0</td><td>2 AZZOLINI</td><td>23</td></tr><tr><td>&gt; 640</td><td>90</td><td>76Ge</td><td>0ν1χ</td><td>GERDA</td><td>3 AGOSTINI</td><td>22</td></tr><tr><td>&gt;4300</td><td>90</td><td>136Xe</td><td>0ν1χ</td><td>EXO-200</td><td>4 AL-KHARUSI</td><td>21</td></tr><tr><td>&gt; 4.4</td><td>90</td><td>100Mo</td><td>0ν1χ</td><td>NEMO-3</td><td>5 ARNOLD</td><td>19</td></tr><tr><td>&gt; 37</td><td>90</td><td>82Se</td><td>0ν1χ</td><td>NEMO-3</td><td>6 ARNOLD</td><td>18</td></tr><tr><td>&gt; 420</td><td>90</td><td>76Ge</td><td>0ν1χ</td><td>GERDA</td><td>7 AGOSTINI</td><td>15A</td></tr><tr><td>&gt; 400</td><td>90</td><td>100Mo</td><td>0ν1χ</td><td>NEMO-3</td><td>8 ARNOLD</td><td>15</td></tr><tr><td>&gt;1200</td><td>90</td><td>136Xe</td><td>0ν1χ</td><td>EXO-200</td><td>9 ALBERT</td><td>14A</td></tr><tr><td>&gt;2600</td><td>90</td><td>136Xe</td><td>0ν1χ</td><td>KamLAND-Zen</td><td>10 GANDO</td><td>12</td></tr><tr><td>&gt; 16</td><td>90</td><td>130Te</td><td>0ν1χ</td><td>NEMO-3</td><td>11 ARNOLD</td><td>11</td></tr><tr><td>&gt; 1.9</td><td>90</td><td>96Zr</td><td>2ν1χ</td><td>NEMO-3</td><td>12 ARGYRIADES</td><td>10</td></tr><tr><td>&gt; 1.52</td><td>90</td><td>150Nd</td><td>0ν1χ</td><td>NEMO-3</td><td>13 ARGYRIADES</td><td>09</td></tr><tr><td>&gt; 27</td><td>90</td><td>100Mo</td><td>0ν1χ</td><td>NEMO-3</td><td>14 ARNOLD</td><td>06</td></tr><tr><td>&gt; 15</td><td>90</td><td>82Se</td><td>0ν1χ</td><td>NEMO-3</td><td>15 ARNOLD</td><td>06</td></tr><tr><td>&gt; 14</td><td>90</td><td>100Mo</td><td>0ν1χ</td><td>NEMO-3</td><td>16 ARNOLD</td><td>04</td></tr><tr><td>&gt; 12</td><td>90</td><td>82Se</td><td>0ν1χ</td><td>NEMO-3</td><td>17 ARNOLD</td><td>04</td></tr><tr><td>&gt; 2.2</td><td>90</td><td>130Te</td><td>0ν1χ</td><td>Cryog. det.</td><td>18 ARNABOLDI</td><td>03</td></tr><tr><td>&gt; 0.9</td><td>90</td><td>130Te</td><td>0ν2χ</td><td>Cryog. det.</td><td>19 ARNABOLDI</td><td>03</td></tr><tr><td>&gt; 8</td><td>90</td><td>116Cd</td><td>0ν1χ</td><td>CdWO<sub>4</sub> scint.</td><td>20 DANEVICH</td><td>03</td></tr><tr><td>&gt; 0.8</td><td>90</td><td>116Cd</td><td>0ν2χ</td><td>CdWO<sub>4</sub> scint.</td><td>21 DANEVICH</td><td>03</td></tr><tr><td>&gt; 500</td><td>90</td><td>136Xe</td><td>0ν1χ</td><td>Liquid Xe Scint.</td><td>22 BERNABEI</td><td>02d</td></tr><tr><td>&gt; 5.8</td><td>90</td><td>100Mo</td><td>0ν1χ</td><td>ELEGANT V</td><td>23 FUSHIMI</td><td>02</td></tr><tr><td>&gt; 0.32</td><td>90</td><td>100Mo</td><td>0ν1χ</td><td>Liq. Ar ioniz.</td><td>24 ASHITKOV</td><td>01</td></tr><tr><td>&gt; 0.0035</td><td>90</td><td>160Gd</td><td>0ν1χ</td><td>160Gd<sub>2</sub>SiO<sub>5</sub>:Ce</td><td>25 DANEVICH</td><td>01</td></tr><tr><td>&gt; 0.013</td><td>90</td><td>160Gd</td><td>0ν2χ</td><td>160Gd<sub>2</sub>SiO<sub>5</sub>:Ce</td><td>26 DANEVICH</td><td>01</td></tr><tr><td>&gt; 2.3</td><td>90</td><td>82Se</td><td>0ν1χ</td><td>NEMO 2</td><td>27 ARNOLD</td><td>00</td></tr><tr><td>&gt; 0.31</td><td>90</td><td>96Zr</td><td>0ν1χ</td><td>NEMO 2</td><td>28 ARNOLD</td><td>00</td></tr><tr><td>&gt; 0.63</td><td>90</td><td>82Se</td><td>0ν2χ</td><td>NEMO 2</td><td>29 ARNOLD</td><td>00</td></tr><tr><td>&gt; 0.063</td><td>90</td><td>96Zr</td><td>0ν2χ</td><td>NEMO 2</td><td>29 ARNOLD</td><td>00</td></tr><tr><td>&gt; 0.16</td><td>90</td><td>100Mo</td><td>0ν2χ</td><td>NEMO 2</td><td>29 ARNOLD</td><td>00</td></tr><tr><td>&gt; 2.4</td><td>90</td><td>82Se</td><td>0ν1χ</td><td>NEMO 2</td><td>30 ARNOLD</td><td>98</td></tr><tr><td>&gt; 7.2</td><td>90</td><td>136Xe</td><td>0ν2χ</td><td>TPC</td><td>31 LUESCHER</td><td>98</td></tr><tr><td>&gt; 7.91</td><td>90</td><td>76Ge</td><td></td><td>SPEC</td><td>32 GUENTHER</td><td>96</td></tr><tr><td>&gt; 17</td><td>90</td><td>76Ge</td><td></td><td>CNTR</td><td>BECK</td><td>93</td></tr></tbody></table>

1. BERNATOWICZ 92 studied double-β decays of $^{128}$Te and $^{130}$Te, and found the ratio $\tau(^{130}_{128}\text{Te})/\tau(^{128}_{128}\text{Te}) = (3.52 \pm 0.11) \times 10^{-4}$ in agreement with relatively stable theoretical predictions. The bound is based on the requirement that Majoron-emitting decay cannot be larger than the observed double-beta rate of $^{128}$Te of $(7.7 \pm 0.4) \times 10^{24}$ year. We calculated 90% CL limit as $(7.7-1.28 \times 0.4=7.2) \times 10^{24}$.

2. AZZOLINI 23 use 9.95 kg·yr of data, collected by the CUPID-0 experiment, to place a limit on the single Majoron mode of the $0\nu\beta\beta$ decay of $^{82}$Se. Various limits on modes involving the emission of multiple Majorons are given too. The resulting constraint on the Majoron-neutrino coupling constant is $g_{\nu\chi} < 1.8-4.4 \times 10^{-5}$. The range is due to the variability of the used nuclear matrix elements.

3. AGOSTINI 22 use 32.8 kg·yr of GERDA phase 2 data to derive a limit of $g_{\nu\chi} < 1.8-4.4 \times 10^{-5}$ on the neutrino-Majoron coupling. The range reflects the author's evaluation of the spread of nuclear matrix elements.

4. AL-KHARUSI 21 utilize the complete dataset of the EXO-200 experiment, corresponding to an exposure of 234 kg yr, to place a limit on the one Majoron mode of the neutrinoless double beta decay of $^{136}$Xe. Several limits are reported, the one given here corresponds to a spectral index of 1, resulting in a limit of $g_{\nu\chi} < 0.4-0.9 \times 10^{-5}$ on the Majoron-neutrino coupling constant. The range reflects the spread of the nuclear matrix elements.

5. ARNOLD 19 uses the NEMO-3 tracking calorimeter to determine limits for the Majoron emitting double beta decay, with spectral index $n = 3$. The limit corresponds to the range of the $g_{ee}$ coupling of 0.013-0.035; depending on the nuclear matrix elements used.

6. ARNOLD 18 use the NEMO-3 tracking detector. The limit corresponds to $\langle g_{ee} \rangle < 3.2-8.0 \times 10^{-5}$; the range corresponds to different nuclear matrix element calculations.

7. AGOSTINI 15A analyze a 20.3 kg yr of data set of the GERDA calorimeter to determine $g_{\nu\chi} < 3.4-8.7 \times 10^{-5}$ on the Majoron-neutrino coupling constant. The range reflects the spread of the nuclear matrix elements.

8. ARNOLD 15 use the NEMO-3 tracking calorimeter with 3.43 kg yr exposure to determine the limit on Majoron emission. The limit corresponds to $g_{\nu\chi} < 1.6-3.0 \times 10^{-4}$. The spread reflects different nuclear matrix elements. Supersedes ARNOLD 06.

9. ALBERT 14A utilize 100 kg yr of exposure of the EXO-200 tracking calorimeter to place a limit on the $g_{\nu\chi} < 0.8-1.7 \times 10^{-5}$ on the Majoron-neutrino coupling constant. The range reflects the spread of the nuclear matrix elements.

10. GANDO 12 use the KamLAND-Zen detector to obtain the limit on the $0\nu\chi$ decay with Majoron emission. It implies that the coupling constant $g_{\nu\chi} < 0.8-1.6 \times 10^{-5}$ depending on the nuclear matrix elements used.

11. ARNOLD 11 use the NEMO-3 detector to obtain the reported limit on Majoron emission. It implies that the coupling constant $g_{\nu\chi} < 0.6-1.0 \times 10^{-4}$ depending on the nuclear matrix element used. Supersedes ARNABOLDI 03.

12. ARGYRIADES 10 use the NEMO-3 tracking detector and $^{96}$Zr to derive the reported limit. No limit for the Majoron electron coupling is given.

13. ARGYRIADES 09 use $^{150}$Nd data taken with the NEMO-3 tracking detector. The reported limit corresponds to $\langle g_{\nu\chi} \rangle < 1.7-3.0 \times 10^{-4}$ using a range of nuclear matrix elements that include the effect of nuclear deformation.

14. ARNOLD 06 use $^{100}$Mo data taken with the NEMO-3 tracking detector. The reported limit corresponds to $\langle g_{\nu\chi} \rangle < (0.4-1.8) \times 10^{-4}$ using a range of matrix element calculations. Superseded by ARNOLD 15.

15. NEMO-3 tracking calorimeter is used in ARNOLD 06. Reported half-life limit for $^{82}$Se corresponds to $\langle g_{\nu\chi} \rangle < (0.66-1.9) \times 10^{-4}$ using a range of matrix element calculations. Supersedes ARNOLD 04.

16. ARNOLD 04 use the NEMO-3 tracking detector. The limit corresponds to $\langle g_{\nu\chi} \rangle < (0.5-0.9) \times 10^{-4}$ using the matrix elements of SIMKOVIC 99, STOICA 01 and CIV-ITARESE 03. Superseded by ARNOLD 06.

17. ARNOLD 04 use the NEMO-3 tracking detector. The limit corresponds to $\langle g_{\nu\chi} \rangle < (0.7-1.6) \times 10^{-4}$ using the matrix elements of SIMKOVIC 99, STOICA 01 and CIV-ITARESE 03.

18. Supersedes ALESSANDRELLO 00. Array of TeO$_2$ crystals in high resolution cryogenic calorimeter. Some enriched in $^{130}$Te. Derive $\langle g_{\nu\chi} \rangle < 17-33 \times 10^{-5}$ depending on matrix element.

19. Supersedes ALESSANDRELLO 00. Cryogenic calorimeter search.

20. Limit for the $0\nu\chi$ decay with Majoron emission of $^{116}$Cd using enriched CdWO$_4$ scintillators. $\langle g_{\nu\chi} \rangle < 4.6-8.1 \times 10^{-5}$ depending on the matrix element. Supersedes DANEVICH 00.

21. Limit for the $0\nu2\chi$ decay of $^{116}$Cd. Supersedes DANEVICH 00.

22. BERNABEI 02D obtain limit for $0\nu\chi$ decay with Majoron emission of $^{136}$Xe using liquid Xe scintillation detector. They derive $\langle g_{\nu\chi} \rangle < 2.0-3.0 \times 10^{-5}$ with several nuclear matrix elements.

23. Replaces TANAKA 93. FUSHIMI 02 derive half-life limit for the $0\nu\chi$ decay by means of tracking calorimeter ELEGANT V. Considering various matrix element calculations, a range of limits for the Majoron-neutrino coupling is given: $\langle g_{\nu\chi} \rangle < (6.3-360) \times 10^{-5}$.

24. ASHITKOV 01 result for $0\nu\chi$ of $^{100}$Mo is less stringent than ARNOLD 00.

25. DANEVICH 01 obtain limit for the $0\nu\chi$ decay with Majoron emission of $^{160}$Gd using Gd$_2$SiO$_5$:Ce crystal scintillators.

26. DANEVICH 01 obtain limit for the $0\nu2\chi$ decay with 2 Majoron emission of $^{160}$Gd.

27. ARNOLD 00 reports limit for the $0\nu\chi$ decay with Majoron emission derived from tracking calorimeter NEMO 2. Using $^{82}$Se source: $\langle g_{\nu\chi} \rangle < 1.6 \times 10^{-4}$. Matrix element from GUENTHER 96.

28. Using $^{96}$Zr source: $\langle g_{\nu\chi} \rangle < 2.6 \times 10^{-4}$. Matrix element from ARNOLD 99.

29. ARNOLD 00 reports limit for the $0\nu2\chi$ decay with two Majoron emission derived from tracking calorimeter NEMO 2.

30. ARNOLD 98 determine the limit for $0\nu\chi$ decay with Majoron emission of $^{82}$Se using the NEMO-2 tracking detector. They derive $\langle g_{\nu\chi} \rangle < 2.3-4.3 \times 10^{-4}$ with several nuclear matrix elements.

31. LUESCHER 98 report a limit for the $0\nu$ decay with Majoron emission of $^{136}$Xe using Xe TPC. This result is more stringent than BARABASH 89. Using the matrix elements of ENGEL 88, they obtain a limit on $\langle g_{\nu\chi} \rangle$ of $2.0 \times 10^{-4}$.

32. See Table 1 in GUENTHER 96 for limits on the Majoron coupling in different models.

## Invisible A⁰ (Axion) MASS LIMITS from Astrophysics and Cosmology

$v_i$ = v$_2$ is usually assumed ($v_i$ = vacuum expectation values). For a review of these limits, see RAFFELT 91 and TURNER 90. In the comment lines below, D and K refer to DFSZ and KSVZ axion types, discussed in the above minireview.

<table><thead><tr><th>VALUE (eV)</th><th>CL%</th><th>DOCUMENT ID</th><th>TECN</th><th>COMMENT</th></tr></thead><tbody><tr><td>• • • We do not use the following data for averages, fits, limits, etc. • • •</td><td></td><td></td><td></td><td></td></tr><tr><td>&gt; 3.2 × 10<sup>-19</sup></td><td>95</td><td>1 CHENG</td><td>23</td><td>ASTR BH superradiance</td></tr><tr><td>&lt;141</td><td>90</td><td>2 DELLA-MON...23</td><td>23</td><td>ASTR Ultralight DM soliton halo core</td></tr><tr><td>&lt; 0.24</td><td>95</td><td>3 DERBIN</td><td>23</td><td>CNTR K, solar axions</td></tr><tr><td>none 10<sup>-24</sup>–5 × 10<sup>-23</sup></td><td>95</td><td>4 NOTARI</td><td>23</td><td>COSM K, Hot dark matter</td></tr><tr><td>none 10<sup>-24</sup>–5 × 10<sup>-23</sup></td><td>95</td><td>5 ROGERS</td><td>23</td><td>COSM Ultra-light axion DM</td></tr><tr><td>none 10<sup>-24</sup>–5 × 10<sup>-23</sup></td><td>95</td><td>6 SMARRA</td><td>23</td><td>EPTA Ultralight DM mass limit</td></tr><tr><td>none 1.3–2.7 × 10<sup>-13</sup></td><td>95</td><td>7 XIA</td><td>23</td><td>ASTR BH superradiance</td></tr><tr><td>&gt; 2 × 10<sup>-20</sup></td><td>95</td><td>8 LAGUE</td><td>22</td><td>COSM Ultralight axion DM</td></tr><tr><td>none 0.8–6.5 × 10<sup>-13</sup></td><td>95</td><td>9 YUAN</td><td>22A</td><td>ASTR BH superradiance</td></tr><tr><td>&gt; 2 × 10<sup>-17</sup></td><td>95</td><td>10 BANIK</td><td>21</td><td>ASTR Fuzzy DM</td></tr><tr><td>&gt; 2.1 × 10<sup>-21</sup></td><td>95</td><td>11 BAUMHOLZ...21</td><td>21</td><td>COSM warm dark matter</td></tr><tr><td>none 6.4–8.0 × 10<sup>-13</sup></td><td>95</td><td>12 CROON</td><td>21</td><td>ASTR SN 1987A, axion-muon coupling</td></tr><tr><td>none 2.9–4.6 × 10<sup>-21</sup></td><td>95</td><td>13 FUJIKURA</td><td>21</td><td>ASTR Microlensing</td></tr><tr><td>none 10<sup>-21</sup>–6 × 10<sup>-20</sup></td><td>95</td><td>14 MARTINCAM...21</td><td>21</td><td>ASTR SN 1987A, A decay</td></tr><tr><td>none 1.1–4 × 10<sup>-13</sup></td><td>95</td><td>15 NG</td><td>21</td><td>ASTR BH superradiance</td></tr><tr><td>&lt; 0.06</td><td>95</td><td>16 ROGERS</td><td>21</td><td>COSM Lyman-α</td></tr><tr><td>&lt; 0.67</td><td>95</td><td>17 TSUKADA</td><td>21</td><td>ASTR BH superradiance</td></tr><tr><td>none 0.7–3 × 10<sup>5</sup></td><td>95</td><td>18 IRSIC</td><td>20</td><td>COSM Isocurvature fluctuations</td></tr><tr><td>&lt;105</td><td>90</td><td>19 PODDAR</td><td>20</td><td>ASTR Compact binary systems</td></tr><tr><td>&lt; 0.72</td><td>95</td><td>20 SCHUTZ</td><td>20</td><td>COSM Fuzzy DM</td></tr><tr><td>&lt;191</td><td>90</td><td>21 SUN</td><td>20</td><td>ASTR BH superradiance</td></tr><tr><td>&lt;191</td><td>90</td><td>22 DAVOUDIASL...19</td><td>19</td><td>ASTR BH superradiance</td></tr><tr><td>&lt;191</td><td>90</td><td>23 MARSH</td><td>19</td><td>ASTR Fuzzy DM</td></tr><tr><td>&lt;191</td><td>90</td><td>24 PALOMBA</td><td>19</td><td>ASTR BH superradiance</td></tr><tr><td>&lt;191</td><td>90</td><td>25 CHANG</td><td>18</td><td>ASTR K, SN 1987A</td></tr><tr><td>&lt;191</td><td>90</td><td>26 PORAYKO</td><td>18</td><td>PPTA Fuzzy DM</td></tr><tr><td>&lt;191</td><td>90</td><td>27 ARCHIDIACO...13A</td><td>18</td><td>COSM K, hot dark matter</td></tr><tr><td>&lt;191</td><td>90</td><td>28 CADAMURO</td><td>11</td><td>COSM D abundance</td></tr><tr><td>&lt;191</td><td>90</td><td>29 DERBIN</td><td>11A</td><td>CNTR D, solar axion</td></tr><tr><td>&lt;191</td><td>90</td><td>30 ANDRIAMON...10</td><td>10</td><td>CAST K, solar axions</td></tr><tr><td>&lt;191</td><td>90</td><td>31 HANNESTAD</td><td>10</td><td>COSM K, hot dark matter</td></tr><tr><td>&lt;191</td><td>90</td><td>32 ANDRIAMON...09</td><td>9</td><td>CAST K, solar axions</td></tr><tr><td>&lt;191</td><td>90</td><td>33 DERBIN</td><td>09A</td><td>CNTR K, solar axions</td></tr></tbody></table>
# Gauge & Higgs Boson Particle Listings
## Axions ($A^0$) and Other Very Light Bosons

<table><tr><td>&lt;334</td><td>95</td><td>34 KEKEZ</td><td>09</td><td>HPGE</td><td>K, solar axions</td></tr><tr><td>&lt; 1.02</td><td>95</td><td>39 HANNESTAD</td><td>08</td><td>COSM</td><td>K, hot dark matter</td></tr><tr><td>&lt; 1.2</td><td>95</td><td>36 HANNESTAD</td><td>07</td><td>COSM</td><td>K, hot dark matter</td></tr><tr><td>&lt; 0.42</td><td>95</td><td>37 MELCHIORRI</td><td>07A</td><td>COSM</td><td>K, hot dark matter</td></tr><tr><td>&lt; 1.05</td><td>95</td><td>38 HANNESTAD</td><td>05A</td><td>COSM</td><td>K, hot dark matter</td></tr><tr><td>3 to 20</td><td></td><td>40 MOROI</td><td>98</td><td>COSM</td><td>K, hot dark matter</td></tr><tr><td>&lt; 0.007</td><td></td><td>40 BORISOV</td><td>97</td><td>ASTR</td><td>D, neutron star</td></tr><tr><td>&lt; 4</td><td></td><td>41 KACHELRIESS</td><td>97</td><td>ASTR</td><td>D, neutron star cooling</td></tr><tr><td>&lt; (0.5-6) × 10<sup>-3</sup></td><td></td><td>42 KEIL</td><td>97</td><td>ASTR</td><td>SN 1987A</td></tr><tr><td>&lt; 0.018</td><td></td><td>43 RAFFELT</td><td>95</td><td>ASTR</td><td>D, red giant</td></tr><tr><td>&lt; 0.010</td><td></td><td>44 ALTHERR</td><td>94</td><td>ASTR</td><td>D, red giants, white dwarfs</td></tr><tr><td>&lt; 0.01</td><td></td><td>45 CHANG</td><td>93</td><td>ASTR</td><td>K, SN 1987A</td></tr><tr><td>&lt; 0.03</td><td></td><td>WANG</td><td>92</td><td>ASTR</td><td>D, white dwarf</td></tr><tr><td>none 3-8</td><td></td><td>WANG</td><td>92C</td><td>ASTR</td><td>D, C-O burning</td></tr><tr><td>&lt; 10</td><td></td><td>46 BERSHADY</td><td>91</td><td>ASTR</td><td>D, K, intergalactic light</td></tr><tr><td></td><td></td><td>47 KIM</td><td>91C</td><td>COSM</td><td>D, K, mass density of the universe, super-symmetry</td></tr><tr><td>&lt; 1 × 10<sup>-3</sup></td><td></td><td>48 RAFFELT</td><td>91B</td><td>ASTR</td><td>D,K, SN 1987A</td></tr><tr><td>none 10<sup>-3</sup>-3</td><td></td><td>49 RESSELL</td><td>91</td><td>ASTR</td><td>K, intergalactic light</td></tr><tr><td>&lt; 0.02</td><td></td><td>BURROWS</td><td>90</td><td>ASTR</td><td>D,K, SN 1987A</td></tr><tr><td>&lt; 1 × 10<sup>-3</sup></td><td></td><td>50 ENGEL</td><td>90</td><td>ASTR</td><td>D,K, SN 1987A</td></tr><tr><td>&lt; (1.4-10) × 10<sup>-3</sup></td><td></td><td>51 RAFFELT</td><td>90</td><td>ASTR</td><td>D, red giant</td></tr><tr><td>&lt; 3.6 × 10<sup>-4</sup></td><td></td><td>52 BURROWS</td><td>89</td><td>ASTR</td><td>D,K, SN 1987A</td></tr><tr><td>&lt; 12</td><td></td><td>53 ERICSON</td><td>89</td><td>ASTR</td><td>D,K, SN 1987A</td></tr><tr><td>&lt; 1 × 10<sup>-3</sup></td><td></td><td>54 MAYLE</td><td>89</td><td>ASTR</td><td>D,K, SN 1987A</td></tr><tr><td>&lt; 0.07</td><td></td><td>CHANDA</td><td>88</td><td>ASTR</td><td>D, Sun</td></tr><tr><td>&lt; 0.03</td><td></td><td>RAFFELT</td><td>88</td><td>ASTR</td><td>D,K, SN 1987A</td></tr><tr><td>&lt; 1</td><td></td><td>55 RAFFELT</td><td>88B</td><td>ASTR</td><td>red giant</td></tr><tr><td>&lt; 0.003-0.02</td><td></td><td>FRIEMAN</td><td>87</td><td>ASTR</td><td>D, red giant</td></tr><tr><td>&gt; 1 × 10<sup>-5</sup></td><td></td><td>56 RAFFELT</td><td>87</td><td>ASTR</td><td>K, red giant</td></tr><tr><td>&gt; 1 × 10<sup>-5</sup></td><td></td><td>TURNER</td><td>87</td><td>COSM</td><td>K, thermal production</td></tr><tr><td>&lt; 0.01</td><td></td><td>57 DEARBORN</td><td>86</td><td>ASTR</td><td>D, red giant</td></tr><tr><td>&lt; 0.06</td><td></td><td>RAFFELT</td><td>86</td><td>ASTR</td><td>D, red giant</td></tr><tr><td>&lt; 0.7</td><td></td><td>58 RAFFELT</td><td>86</td><td>ASTR</td><td>K, red giant</td></tr><tr><td>&lt; 0.03</td><td></td><td>RAFFELT</td><td>86B</td><td>ASTR</td><td>D, white dwarf</td></tr><tr><td>&lt; 1</td><td></td><td>59 KAPLAN</td><td>85</td><td>ASTR</td><td>K, red giant</td></tr><tr><td>&lt; 0.003-0.02</td><td></td><td>IWAMOTO</td><td>84</td><td>ASTR</td><td>D, K, neutron star</td></tr><tr><td>&gt; 1 × 10<sup>-5</sup></td><td></td><td>ABBOTT</td><td>83</td><td>COSM</td><td>D,K, mass density of the universe</td></tr><tr><td>&gt; 1 × 10<sup>-5</sup></td><td></td><td>DINE</td><td>83</td><td>COSM</td><td>D,K, mass density of the universe</td></tr><tr><td>&lt; 0.04</td><td></td><td>ELLIS</td><td>83B</td><td>ASTR</td><td>D, red giant</td></tr><tr><td>&gt; 1 × 10<sup>-5</sup></td><td></td><td>PRESKILL</td><td>83</td><td>COSM</td><td>D,K, mass density of the universe</td></tr><tr><td>&lt; 0.1</td><td></td><td>BARROSO</td><td>82</td><td>ASTR</td><td>D, red giant</td></tr><tr><td>&lt; 1</td><td></td><td>60 FUKUGITA</td><td>82</td><td>ASTR</td><td>D, stellar cooling</td></tr><tr><td>&lt; 0.07</td><td></td><td>FUKUGITA</td><td>82B</td><td>ASTR</td><td>D, red giant</td></tr></table>

1 CHENG 23 employ an improved approximation of the boson cloud eigenfrequency to calculate the superradiance rate. They find that sensitivity depends on initial spin distribution and the merger timescale, and identify two preferred ranges for boson mass centered at $1.78 \times 10^{-12}$ and $7.94 \times 10^{-13}$ eV.

2 DELLA-MONICA 23 consider the solitonic core implied by ultralight scalar dark matter in the centre of the Milky Way and the effect its presence would have on the precisely tracked orbits of the stars orbiting our galaxy's central supermassive black hole, Sagittarius A*.

3 DERBIN 23 employ a thulium garnet crystal bolometer to search for the 8.4 keV solar axion line emitted from the M1 nuclear transition of thulium-169,¹⁶⁹Tm. Mass bound applies to KSVZ axions, value for DFSZ is 244 eV.

4 NOTARI 23 improved the evaluation of axion production from pion scatterings by using pion-pion scattering data and incorporating the momentum dependence of the Boltzmann equation. The limit is based on the Planck 2018, BAO, and Pantheon SN la data.

5 ROGERS 23 use the CMB and BOSS galaxy-clustering data to set limits on the abundance of ultralight axion DM. They obtained $\Omega_{A^0} < 0.002$ for $m_{A^0} = 10^{-30}-10^{-28}$ eV and set upper limits ranging from 0.002 to 0.07 for $m_{A^0} = 10^{-32}-10^{-25}$ eV. See their Fig. 22 for mass-dependent limits.

6 SMARRA 23 is the European Pulsar Timing Array's constraint on the contribution of ultralight DM to the DM density in our local galactic neighbourhood. Ultralight DM cannot saturate the known DM density of 0.3 GeV/cc for masses inside this mass interval of $10^{-24}-5 \times 10^{-23}$ eV.

7 XIA 23 is analogous to PORAYKO 18 and use the Fermi-LAT pulsar timing array. They set a bound on the local density as $\rho_{A^0} \lesssim 8 \text{ GeV/cm}^3$ for $m_{A^0} \lesssim 10^{-23}$ eV at 95% CL, with weaker constraints up to $10^{-22}$ eV. See their Fig. 1 for the mass-dependent limits.

8 LAGUE 22 used the BOSS galaxy-clustering data to set limits on the abundance of ultralight axion dark matter. When combined with the CMB data, they obtained $\Omega_{A^0} h^2 < 0.004$ for $m_{A^0} = 10^{-31}-10^{-26}$ eV. See their Figs. 1 and 15 for mass-dependent limits.

9 YUAN 22a use the data of Advanced LIGO and Advanced Virgo's first three observing runs to search for stochastic GW background produced by scalar bosonic clouds formed by the BH superradiant instability. They set the limit, taking into account all the unstable modes.

10 BANIK 21 use the subhalo mass function inferred from the analyses of the GD-1 and Pal 5 stellar streams. The limit is strengthened to $2.2 \times 10^{-21}$ eV when adding dwarf satellite counts.

11 BAUMHOLZER 21 study the freeze-in production of axion dark matter through couplings to photons, and set the limit using Lyman-$\alpha$ forest data and the observed number of Milky Way subhalos.

12 CROON 21 study the supernova cooling effect of the axion-muon coupling, taking account of semi-Compton scattering and muon-proton bremsstrahlung, as well as the loop-induced axion-photon coupling, and exclude the range of $g_{A\mu\mu} \simeq 7 \times 10^{-3}-2 \times 10^{-10}$ for $m_{A^0} < 0.5$ GeV. See their Fig. 8 for mass-dependent limits.

13 FUJIKURA 21 use the EROS-2 survey and the Subaru HSC observation to set limits on spherically symmetric axion clumps, taking account of the finite lens and source size effects. $f_{A^0} \gtrsim 10^{12}$ GeV can be constrained depending on the fraction of the axion dark matter collapsed into clumps, and the clump densities. See their Figs. 7-10 for the limits.

14 MARTINCAMALICH 21 considered axion emission from a supernova core through the $\Lambda$ hyperon decay, and set the limit on $B(\Lambda \rightarrow nA^0) \lesssim 8 \times 10^{-9}$, or equivalently, $f_{A^0}/c_{sd} \gtrsim 2.6 \times 10^9$ GeV in terms of the flavor-violating axion coupling to the down and strange quarks.

15 NG 21 use the binary black holes reported by LIGO and Virgo to determine the black hole spin distribution at formation and the scalar boson mass simultaneously, neglecting the boson self-interaction.

16 ROGERS 21 set the limit by using a framework involving Bayesian emulator optimization to accurately forward-model the Lyman-$\alpha$ flux power spectrum, and comparing this with small-scale data to constrain the predicted suppression of cosmic structure growth.

17 TSUKADA 21 look for a stochastic GW background produced by extragalactic BH-hidden photon cloud systems through the superradiant instability. They assume a uniform spin distribution at birth of isolated BHs from 0 to 1.

18 IRSIC 20 used the Lyman-$\alpha$ forest constraint on small-scale isocurvature perturbation to derive limits on the axion mass and decay constant, assuming that the axion makes up all dark matter in the post-inflationary scenario. See their Fig. 1 for other astrophysical limits as well as the limits on the case of the temperature-dependent axion mass.

19 PODDAR 20 used the observed decay in orbital period of four compact binary systems to derive a limit on the emission of axions with $m_{A^0} < 1 \times 10^{-19}$ eV, assuming they couple to nucleons and the strong CP phase vanishes at the potential minimum. They exclude $f_{A^0} \lesssim 10^{11}$ GeV for such axions.

20 SCHUTZ 20 set a limit on fuzzy dark matter based on the existing limits for warm dark matter derived from the inferred subhalo mass function.

21 SUN 20 look for quasimonochromatic gravitational waves emitted from boson clouds around the Cygnus X-1 black hole. The quoted limit assumes the black hole age of 5 × 10⁹ years. A mass range of 9.6-15.5 × 10⁻¹³ eV is disfavored when repeated induction of bosenova for string axions with decay constant $f_{A^0} \simeq 10^{15}$ GeV prevents the superradiance from being saturated.

22 DAVOUDIASL 19 used the observed data of M87* by the Event Horizon Telescope to set the limit. A mass range of 0.85-4.6 × 10⁻²¹ eV is disfavored for a spin-1 boson.

23 MARSH 19 considered heating of star clusters due to the stochastic oscillations of the core and granular quasiparticles in the outer halo. The limit was derived by requiring the survival of the old star cluster in Eridanus II, where the lower end is set by the validity of diffusion approximation. The effect of tidal stripping is also discussed for lower masses.

24 PALOMBA 19 used the LIGO O2 dataset to derive limits on nearly monochromatic gravitational waves emitted by boson clouds formed around a stellar-mass black hole. They exclude boson masses in a range of $1.1 \times 10^{-13}$ and $4 \times 10^{-13}$ eV for high initial black hole spin, and $1.2 \times 10^{-13}$ and $1.8 \times 10^{-13}$ eV for moderate spin. See their Figs. 2 and 3 for limits based on various values of black hole initial spin, boson cloud age, and distance.

25 CHANG 18 update axion bremsstrahlung emission rates in nucleon-nucleon collisions, shifting the excluded mass range to higher values. They rule out the hadronic axion with mass up to a few hundred eV, closing the hadronic axion window. See their Fig. 11 for results based on several different choices of the temperature and density profile of the proto-neutron star.

26 PORAYKO 18 look for time-dependent oscillations in the gravitational potential generated by ultralight scalar dark matter, and set a bound on its local density as $\rho_{A^0} \lesssim 6$ GeV/cm³ for $m_{A^0} \lesssim 10^{-23}$ eV at 95% CL. See their Fig. 4 for the limits.

27 ARCHIDIACONO 13A is analogous to HANNESTAD 05A. The limit is based on the CMB temperature power spectrum of the Planck data, the CMB polarization from the WMAP 9-yr data, the matter power spectrum from SDSS-DR7, and the local Hubble parameter measurement by the Carnegie Hubble program.

28 CADAMURO 11 use the deuterium abundance to show that the $m_{A^0}$ range 0.7 eV - 300 keV is excluded for axions, complementing HANNESTAD 10.

29 DERBIN 11A look for solar axions produced by Compton and bremsstrahlung processes, in the resonant excitation of ¹⁶⁹Tm, constraining the axion-electron × axion nucleon couplings.

30 ANDRIAMONJE 10 search for solar axions produced from $^7$Li (478 keV) and $D(\rho, \gamma)^3$He (5.5 keV) nuclear transitions. They show limits on the axion-photon coupling for two reference values of the axion-nucleon coupling for $m_A < 100$ eV.

31 This is an update of HANNESTAD 08 including 7 years of WMAP data.

32 ANDRIAMONJE 09 look for solar axions produced from the thermally excited 14.4 keV level of $^{57}$Fe. They show limits on the axion-nucleon × axion-photon coupling assuming $m_A < 0.03$ eV.

33 DERBIN 09A look for Primakoff-produced solar axions in the resonant excitation of ¹⁶⁹Tm, constraining the axion-photon × axion-nucleon couplings.

34 KEKEZ 09 look at axio-electric effect of solar axions in HPGe detectors. The one-loop axion-electron coupling for hadronic axions is used.

35 This is an update of HANNESTAD 07 including 5 years of WMAP data.

36 This is an update of HANNESTAD 05A with new cosmological data, notably WMAP (3 years) and baryon acoustic oscillations (BAO). Lyman-$\alpha$ data are left out, in contrast to HANNESTAD 05A and MELCHIORRI 07A, because it is argued that systematic errors are large. It uses Bayesian statistics and marginalizes over a possible neutrino hot dark matter component.

37 MELCHIORRI 07A is analogous to HANNESTAD 05A, with updated cosmological data, notably WMAP (3 years). Uses Bayesian statistics and marginalizes over a possible neutrino hot dark matter component. Leaving out Lyman-$\alpha$ data, a conservative limit is 1.4 eV.

38 HANNESTAD 05A puts an upper limit on the mass of hadronic axion because in this mass range it would have been thermalized and contribute to the hot dark matter component of the universe. The limit is based on the CMB anisotropy from WMAP, SDSS large scale structure, Lyman-$\alpha$, and the prior Hubble parameter from HST Key Project. A $\chi^2$ statistic is used. Neutrinos are assumed not to contribute to hot dark matter.