Citation: S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)

J = 12ee MASS (atomic mass units u)
The primary determination of an electron’s mass comes from measuring
the ratio of the mass to that of a nucleus, so that the result is obtained inu (atomic mass units). The conversion factor to MeV is more uncertain
than the mass of the electron in u; indeed, the recent improvements inthe mass determination are not evident when the result is given in MeV.
In this datablock we give the result in u, and in the following datablock inMeV.

VALUE (10−6 u)

DOCUMENT ID

TECNCOMMENT

548.579909065± 0.000000016
TIESINGA
21 RVUE 2018 CODATA value• • • We do not use the following data for averages, fits, limits, etc. • • •548.579909070± 0.000000016
MOHR
16 RVUE 2014 CODATA value
548.57990946 ± 0.00000022
MOHR
12 RVUE 2010 CODATA value
548.57990943 ± 0.00000023
MOHR
08 RVUE 2006 CODATA value
548.57990945 ± 0.00000024
MOHR
05 RVUE 2002 CODATA value
1 BEIER
548.5799092 ± 0.0000004
02 CNTR Penning trap
548.5799110 ± 0.0000012
MOHR
99 RVUE 1998 CODATA value
2 FARNHAM
548.5799111 ± 0.0000012
95 CNTR Penning trap
548.579903± 0.000013
COHEN
87 RVUE 1986 CODATA value
1 BEIER 02 compares Larmor frequency of the electron bound in a 12 C5+ ion with thecyclotron frequency of a single trapped 12 C5+ ion.
2 FARNHAM 95 compares cyclotron frequency of trapped electrons with that of a single
trapped 12 C6+ ion.

e MASS
The mass is known more precisely in u (atomic mass units) than in MeV.
The conversion is: 1 u = 931.494 102 42(28) MeV/c2 (2018 CODATA
value, TIESINGA 21). The conversion error dominates the uncertainty ofthe masses given below.

VALUE (MeV)

DOCUMENT ID

TECNCOMMENT

0.51099895000± 0.00000000015
TIESINGA
21 RVUE 2018 CODATA value• • • We do not use the following data for averages, fits, limits, etc. • • •0.5109989461 ± 0.0000000031
0.510998928 ± 0.000000011
0.510998910 ± 0.000000013
0.510998918 ± 0.000000044
0.510998901 ± 0.000000020
0.510998902 ± 0.000000021
0.510998903 ± 0.000000020
0.510998895 ± 0.000000024
0.5110034± 0.0000014

MOHR
MOHR
MOHR
MOHR
1,2 BEIER
MOHR
1,3 FARNHAM
1 COHEN
COHEN

https://pdg.lbl.gov

Page 1161208
0502
99958773

RVUE
RVUE
RVUE
RVUE
CNTR
RVUE
CNTR
RVUE
RVUE

2014 CODATA value
2010 CODATA value
2006 CODATA value
2002 CODATA value
Penning trap
1998 CODATA value
Penning trap
1986 CODATA value
1973 CODATA value

Created: 5/31/2024 10:15

Citation: S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)

1 Converted to MeV using the 1998 CODATA value of the conversion constant,
931.494013 ± 0.000037 MeV/u.
2 BEIER 02 compares Larmor frequency of the electron bound in a 12 C5+ ion with thecyclotron frequency of a single trapped 12 C5+ ion.
3 FARNHAM 95 compares cyclotron frequency of trapped electrons with that of a single
trapped 12 C6+ ion.

(m e + − m e − ) / m average
A test of CPT invariance.
VALUE

CL%

DOCUMENT ID

TECNCOMMENT

1 FEE<8 × 10−990
93 CNTR Positronium spectroscopy• • • We do not use the following data for averages, fits, limits, etc. • • •2 DOLGOV<4 × 10−2390
14From photon mass limit−8<4 × 1090
CHU
84 CNTR Positronium spectroscopy
1 FEE 93 value is obtained under the assumption that the positronium Rydberg constantis exactly half the hydrogen one.
2 DOLGOV 14 result is obtained under the assumption that any mass difference between
electron and positron would lead to a non-zero photon mass. The PDG 12 limit of
1 × 10−18 eV on the photon mass is in turn used to derive the value quoted here.

qe + + qe − eA test of CPT invariance. See also similar tests involving the proton.
VALUE

DOCUMENT ID

TECNCOMMENT

1 HUGHES<4 × 10−892 RVUE• • • We do not use the following data for averages, fits, limits, etc. • • •2 SCHAEFER<2 × 10−18
95 THEO Vacuum polarization−183<1 × 10MUELLER
92 THEO Vacuum polarization
1 HUGHES 92 uses recent measurements of Rydberg-energy and cyclotron-frequency ratios.
2 SCHAEFER 95 removes model dependency of MUELLER 92.
3 MUELLER 92 argues that an inequality of the charge magnitudes would, through higherorder vacuum polarization, contribute to the net charge of atoms.

e MAGNETIC MOMENT ANOMALYµe /µB − 1 = (g−2)/2
VALUE (units 10−6 )DOCUMENT ID

TECN

CHG

COMMENT

1159.65218062± 0.00000012 OUR AVERAGE
1 FAN
1159.65218059± 0.00000013
23 MRS
Single electron
1159.65218073± 0.00000028
HANNEKE08 MRS
Single electron
1159.6521884 ± 0.0000043
VANDYCK87 MRS −Single electron• • • We do not use the following data for averages, fits, limits, etc. • • •1159.65218128± 0.00000018
1159.65218091± 0.00000026
1159.65218076± 0.00000027
1159.65218111± 0.00000074

https://pdg.lbl.gov

TIESINGA
MOHR
MOHR
2 MOHR

Page 221161208

RVUE
RVUE
RVUE
RVUE

2018 CODATA value
2014 CODATA value
2010 CODATA value
2006 CODATA value

Created: 5/31/2024 10:15

Citation: S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)

3 ODOM
1159.65218085± 0.00000076
06 MRS −Single electron
1159.6521859 ± 0.0000038
MOHR
05 RVUE2002 CODATA value
1159.6521869 ± 0.0000041
MOHR
99 RVUE1998 CODATA value
1159.652193 ± 0.000010
COHEN
87 RVUE1986 CODATA value
4 VANDYCK
1159.6521879 ± 0.0000043
87 MRS +Single positron
1 FAN 23 report the most accurate measurement of the electron magnetic moment. A
one-electron quantum cyclotron is used. We do not propagate at the moment thismeasurement to the fine structure and other physical constants. When discrepancies in
the independent determinations of alpha are resolved, the new measurement uncertaintyof 0.13 ppt is available for precise tests for BSM physics.
2 MOHR 08 average is dominated by ODOM 06.
3 Superseded by HANNEKE 08 per private communication with Gerald Gabrielse.
4 This VANDYCK 87 reault is for a positron. We do not take it into account for theaverage to avoid the assumption of CPT invariance.

(g e + − g e − ) / gaverage
A test of CPT invariance.
VALUE (units 10−12 )CL%

DOCUMENT ID

TECNCOMMENT

1 VANDYCK− 0.5± 2.1
87 MRS Penning trap• • • We do not use the following data for averages, fits, limits, etc. • • •2 VASSERMAN 87 CNTR Assumes m< 1295=m −e+e22 ± 64
SCHWINBERG 81 MRS Penning trap
1 VANDYCK 87 measured (g /g )− 1 and we converted it.
− +2 VASSERMAN 87 measured (g − g )/(g −2). We multiplied by (g −2)/g = 1.2 ×+−10−3 .

e ELECTRIC DIPOLE MOMENT (d)A nonzero value is forbidden by both T invariance and P invariance.
VALUE (10−28 e cm)

0.041

CL%

https://pdg.lbl.gov

90

DOCUMENT ID

1 ROUSSYTECNPage 323COMMENT

electrons in intramolecularelectric field• • • We do not use the following data for averages, fits, limits, etc. • • •2 ANDREEV<0.1190
18 CNTR ThO molecules
3 CAIRNCROSS 17 ESR
180 Hf19 F<1.390molecules− 5570± 7980 ± 120
KIM
15 CNTR Gd3 Ga5 O12molecules
4 BARON<0.8790
14 CNTR ThO molecules
5 ECKEL< 605090
12 CNTR Eu0.5 Ba0.5 TiO3molecules
6 HUDSON<10.590
11 NMR YbF molecules
6.9 ±
7.4
REGAN
02 MRS 205 Tl beams
7 COMMINS
18±12 ± 1094 MRS 205 Tl beams
7−27±83
ABDULLAH
90 MRS 205 Tl beams− 1400± 2400
CHO
89 NMR TlF molecules− 150± 550 ± 150
MURTHY
89Cs, no B field<ESR

Created: 5/31/2024 10:15

Citation: S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)− 5000± 11000
LAMOREAUX 87 NMR 199 Hg
19000± 3400090
SANDARS
75 MRS Thallium7000± 22000
90
PLAYER
70 MRS Xenon< 3000090
WEISSKOPF 68 MRS Cesium
1 ROUSSY 23 gives a measurement corresponding to this limit as (− 1.3 ± 2.0 ± 0.6) ×10−30 ecm.
2 ANDREEV 18 gives a measurement corresponding to this limit as (4.3 ± 3.1 ± 2.6) ×
10−30 ecm.
3 CAIRNCROSS 17 gives a measurement corresponding to this limit as (0.09 ± 0.77 ±0.17) × 10−28 ecm.
4 BARON 14 gives a measurement corresponding to this limit as (− 0.21 ± 0.37 ± 0.25) ×
10−28 ecm.
5 ECKEL 12 gives a measurement corresponding to this limit as (− 1.07 ± 3.06 ± 1.74) ×
10−25 ecm.
6 HUDSON 11 gives a measurement corresponding to this limit as (− 2.4 ± 5.7 ± 1.5) ×10−28 ecm.
7 ABDULLAH 90, COMMINS 94, and REGAN 02 use the relativistic enhancement of avalence electron’s electric dipole moment in a high-Z atom.

e − MEAN LIFE / BRANCHING FRACTION
A test of charge conservation. See the “Note on Testing Charge Conservation and the Pauli Exclusion Principle” following this section in our 1992
edition (Physical Review D45 S1 (1992), p. VI.10).
Most of these experiments are one of three kinds: Attempts to observe(a) the 255.5 keV gamma ray produced in e − → νe γ, (b) the (K) shell
x ray produced when an electron decays without additional energy deposit,
e.g., e − → νe ν e νe (“disappearance” experiments), and (c) nuclear deexcitation gamma rays after the electron disappears from an atomic shelland the nucleus is left in an excited state. The last can include both weakboson and photon mediating processes. We use the best e − → νe γ limit
for the Summary Tables.
Note that we use the mean life rather than the half life, which is often
reported.

e → νe γ and astrophysical limits
VALUE (yr)

CL%

DOCUMENT ID

TECNCOMMENT>6.6 × 1028
90
AGOSTINI
15B BORX e − → ν γ• • • We do not use the following data for averages, fits, limits, etc. • • •1 KLAPDOR-K... 07 CNTR e − → ν γ>1.22 × 1026
68>4.6 × 102690
BACK02 BORX e − → ν γ
26>3.4 × 1068
BELLI00B DAMA e − → ν γ, liquid Xe25>3.7 × 1068
AHARONOV 95B CNTR e − → ν γ
25>2.35 × 1068
BALYSH93 CNTR e − → ν γ, 76 Ge detector>1.5 × 1025
68
AVIGNONE86 CNTR e − → ν γ392>1× 10ORITO
85 ASTR Astrophysical argument>3× 1023
68BELLOTTI
83B CNTR e − → ν γ
1 The authors of A. Derbin et al, arXiv:0704.2047v1 argue that this limit is overestimatedby at least a factor of 5.
2 ORITO 85 assumes that electromagnetic forces extend out to large enough distances andthat the age of our galaxy is 1010 years.

https://pdg.lbl.gov

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Citation: S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)

Disappearance and nuclear-de-excitation experiments
VALUE (yr)

CL%

DOCUMENT ID

TECNCOMMENT

1 BELLI>6.4 × 1024
68
99B DAMA De-excitation of 129 Xe• • • We do not use the following data for averages, fits, limits, etc. • • •>1.2 × 1024
90
ABGRALL
17 HPGE Ge K-shell disappearance>4.2 × 1024
68
BELLI
99 DAMA Iodine L-shell disappearance
232>2.4 × 1090
BELLI
99D DAMA De-excitation of 127 I (in NaI)
23>4.3 × 10
68
AHARONOV 95B CNTR Ge K-shell disappearance>2.7 × 1023
68
REUSSER
91 CNTR Ge K-shell disappearance>2 × 1022
68BELLOTTI
83B CNTR Ge K-shell disappearance
1 BELLI 99B limit on charge nonconserving e − capture involving excitation of the 236.1
keV nuclear state of 129 Xe; the 90% CL limit is 3.7 × 1024 yr. Less stringent limits forother states are also given.
2 BELLI 99D limit on charge nonconserving e − capture involving excitation of the 57.6
keV nuclear state of 127 I. Less stringent limits for the other states and for the state of23 Na are also given.

LIMITS ON LEPTON-FLAVOR VIOLATION IN PRODUCTION
Forbidden by lepton family number conservation.
This section was added for the 2008 edition of this Review and is notcomplete. For a list of further measurements see references in the papers
listed below.

σ(e + e − → e ± τ ∓ ) / σ(e + e − → µ+ µ− )
VALUE

CL%

DOCUMENT ID

TECNCOMMENT<8.9 × 10−695
AUBERT07P BABR e + e − at E cm = 10.58 GeV• • • We do not use the following data for averages, fits, limits, etc. • • •<1.8 × 10−395
GOMEZ-CAD... 91 MRK2 e + e − at E cm = 29 GeVσ(e + e − → µ± τ ∓ ) / σ(e + e − → µ+ µ− )
VALUE

CL%

DOCUMENT ID

TECNCOMMENT<4.0 × 10−695
AUBERT
07P BABR e + e − at E cm = 10.58 GeV• • • We do not use the following data for averages, fits, limits, etc. • • •<6.1 × 10−395
GOMEZ-CAD... 91 MRK2 e + e − at E cm = 29 GeV

e REFERENCES
FAN
ROUSSYTIESINGAANDREEVABGRALLCAIRNCROSSMOHR
AGOSTINIKIM
BARON
DOLGOV
ECKEL
MOHR
PDG
HUDSON

2323211817171615B15141412121211

PRL 130 071801
SCI 381 46
RMP 93 025010
NAT 562 355
PRL 118 161801
PRL 119 153001
RMP 88 035009
PRL 115 231802
PR D91 102004
SCI 343 269
PL B732 244
PRL 109 193003
RMP 84 1527
PR D86 010001
NAT 473 493

https://pdg.lbl.gov

X. Fan et al.
(HARV, NWES)
T.S. Roussy et al.
(COLO)
E. Tiesinga et al.
(NIST)
V. Andreev et al.
(ACME Collab.)
N. Abgrall et al.
(MAJORANA Collab.)
W.B. Cairncross et al.
(NIST,COLO)
P.J. Mohr, D.B. Newell, B.N. Taylor(NIST)
M. Agostini et al.
(Borexino Collab.)
Y.J. Kim et al.
(IND, YALE, LANL)
J. Baron et al.
(ACME Collab.)
A.D. Dolgov, V.A. Novikov
S. Eckel, A.O. Sushkov, S.K. Lamoreaux(YALE)
P.J. Mohr, B.N. Taylor, D.B. Newell(NIST)
J. Beringer et al.
(PDG Collab.)
J.J. Hadson et al.
(LOIC)

Page 5Created: 5/31/2024 10:15

Citation: S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)

HANNEKE08
MOHR08AUBERT07P
KLAPDOR-K... 07ODOM
06
MOHR
05
BACK
02
BEIER
02
REGAN
02
BELLI
00B
BELLI
99
BELLI
99B
BELLI
99D
MOHR
99
Also
AHARONOV
95B
Also
FARNHAM95
SCHAEFER
95
COMMINS94
BALYSH93
FEE
93
HUGHES
92
MUELLER
92
PDG
92
GOMEZ-CAD... 91
REUSSER91
ABDULLAH
90
CHO
89
MURTHY89
COHEN
87
LAMOREAUX 87
VANDYCK87
VASSERMAN 87
Also
AVIGNONE
86
ORITO
85
CHU
84
BELLOTTI
83B
SCHWINBERG 81
SANDARS75
COHEN
73
PLAYER70
WEISSKOPF
68

PRL 100 120801
RMP 80 633
PR D75 031103
PL B644 109
PRL 97 030801RMP 77 1
PL B525 29
PRL 88 011603
PRL 88 071805
PR D61 117301
PL B460 236
PL B465 315
PR C60 065501
JPCRD 28 1713
RMP 72 351
PR D52 3785
PL B353 168
PRL 75 3598
PR A51 838
PR A50 2960
PL B298 278
PR A48 192
PRL 69 578
PRL 69 3432
PR D45 S1
PRL 66 1007
PL B255 143
PRL 65 2347
PRL 63 2559
PRL 63 965
RMP 59 1121
PRL 59 2275
PRL 59 26
PL B198 302
PL B187 172
PR D34 97
PRL 54 2457
PRL 52 1689
PL 124B 435
PRL 47 1679
PR A11 473
JPCRD 2 664
JP B3 1620
PRL 21 1645

https://pdg.lbl.gov

D. Hanneke, S. Fogwell, G. Gabrielse(HARV)
P.J. Mohr, B.N. Taylor, D.B. Newell(NIST)
B. Aubert et al.
(BABAR Collab.)
H.V. Klapdor-Kleingrothaus, I.V. Krivosheina, I.V. Titkova
B. Odom et al.
(HARV)
P.J. Mohr, B.N. Taylor(NIST)
H.O. Back et al.
(Borexino/SASSO Collab.)
T. Beier et al.
B.C. Regan et al.
P. Belli et al.
(DAMA Collab.)
P. Belli et al.
(DAMA Collab.)
P. Belli et al.
(DAMA Collab.)
P. Belli et al.
(DAMA Collab.)P.J. Mohr, B.N. Taylor(NIST)
P.J. Mohr, B.N. Taylor(NIST)Y. Aharonov et al.
(SCUC, PNL, ZARA+)
Y. Aharonov et al.
(SCUC, PNL, ZARA+)
D.L. Farnham, R.S. van Dyck, P.B. Schwinberg (WASH)
A. Schaefer, J. Reinhardt(FRAN)
E.D. Commins et al.
A. Balysh et al.
(KIAE, MPIK, SASSO)
M.S. Fee et al.
R.J. Hughes, B.I. Deutch(LANL, AARH)
B. Muller, M.H. Thoma(DUKE)
K. Hikasa et al.
(KEK, LBL, BOST+)J.J. Gomez-Cadenas et al.
(SLAC MARK-2 Collab.)
D. Reusser et al.
(NEUC, CIT, PSI)
K. Abdullah et al.
(LBL, UCB)
D. Cho, K. Sangster, E.A. Hinds(YALE)
S.A. Murthy et al.
(AMHT)
E.R. Cohen, B.N. Taylor(RISC, NBS)
S.K. Lamoreaux et al.
(WASH)
R.S. van Dyck, P.B. Schwinberg, H.G. Dehmelt (WASH)
I.B. Vasserman et al.
(NOVO)
I.B. Vasserman et al.
(NOVO)
F.T. Avignone et al.
(PNL, SCUC)
S. Orito, M. Yoshimura(TOKY, KEK)
S. Chu, A.P. Mills, J.L. Hall(BELL, NBS, COLO)
E. Bellotti et al.
(MILA)
P.B. Schwinberg, R.S. van Dyck, H.G. Dehmelt (WASH)
P.G.H. Sandars, D.M. Sternheimer(OXF, BNL)
E.R. Cohen, B.N. Taylor(RISC, NBS)
M.A. Player, P.G.H. Sandars(OXF)
M.C. Weisskopf et al.
(BRAN)

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