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

I (J P ) = 0( 21 − ) Status:

Λ(1405) 1/2−∗∗∗∗In the 1998 Note on the Λ(1405) in PDG 98, R.H. Dalitz discussed
the S-shaped cusp behavior of the intensity at the N-K threshold observed in THOMAS 73 and HEMINGWAY 85. He commented that
this behavior ”is characteristic of S-wave coupling; the other below
threshold hyperon, the Σ (1385), has no such threshold distortion
because its N-K coupling is P-wave. For Λ(1405) this asymmetry isthe sole direct evidence that J P = 1/2− .”A recent measurement by the CLAS collaboration, MORIYA 14,
definitively established the long-assumed J P = 1/2− spin-parity
assignment of the Λ(1405).
The experiment produced theΛ(1405) spin-polarized in the photoproduction process γ p →K + Λ(1405) and measured the decay of the Λ(1405) (polarized) →Σ + (polarized) π − . The observed isotropic decay of Λ(1405) is
consistent with spin J = 1/2. The polarization transfer to theΣ + (polarized) direction revealed negative parity, and thus established J P = 1/2− .

See the related review(s):Pole Structure of the Λ(1405) RegionΛ(1405) POLE POSITIONREAL PARTVALUE (MeV)

DOCUMENT ID

TECN• • • We do not use the following data for averages, fits, limits, etc. • • •+ 6.0 + 1.1
1417.7 −7.4 − 1.081429 +− 71434 ± 231421 +− 271424 +− 23
1 Solution number 4.
2 Solution number 2.

AIKAWA

23DPWA

1 MAI

15

DPWA

2 MAI

15DPWA

GUO

13DPWA

IKEDA

12DPWA−2×IMAGINARY PARTVALUE (MeV)

DOCUMENT ID

TECN• • • We do not use the following data for averages, fits, limits, etc. • • •12.0 + 3.452.2 +− 15.8 − 4.0424 +− 6420 +− 2

https://pdg.lbl.gov

AIKAWA

23DPWA

1 MAI

15

DPWA

2 MAI

15

DPWA

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

1638 +− 10652 +− 28
1 Solution number 4.
2 Solution number 2.

GUO

13

DPWA

IKEDA

12DPWAΛ(1405) MASSPRODUCTION EXPERIMENTS
VALUE (MeV)EVTS

DOCUMENT ID

TECNCOMMENT+ 1.3 OUR AVERAGE
1405.1 −1.0111405 +HASSANVAND 13 SPEC p p → p Λ(1405) K +− 91.41405 +ESMAILI
10 RVUE 4 He K − → Σ ± π ∓ X at rest
− 1.01 DALITZ
1406.5± 4.091
M-matrix fit• • • We do not use the following data for averages, fits, limits, etc. • • •1 HEMINGWAY 85 HBC
1391 ± 1700
K − p 4.2 GeV/c2 THOMAS∼ 140540073 HBC
π − p 1.69 GeV/c1405120
BARBARO-... 68B DBC
K − d 2.1–2.7 GeV/c
1400 ± 567BIRMINGHAM 66 HBC
K − p 3.5 GeV/c1382 ± 8
ENGLER
65 HDBC π − p, π + d 1.68 GeV/c
1400 ± 24
MUSGRAVE
65 HBCp p 3–4 GeV/c1410
ALEXANDER 62 HBC
π − p 2.1 GeV/c1405
ALSTON
62 HBCK − p 1.2–0.5 GeV/c1405
ALSTON61B HBCK − p 1.15 GeV/c
1 DALITZ 91 fits the HEMINGWAY 85 data.
2 THOMAS 73 data is fit by CHAO 73 (see next section).

EXTRAPOLATIONS BELOW N K THRESHOLD
VALUE (MeV)

DOCUMENT ID

TECNCOMMENT• • • We do not use the following data for averages, fits, limits, etc. • • •1 KIMURA
1407.56 or 1407.50
00
potential model
2 MARTIN
1411
81K-matrix fit
3 CHAO1406
73 DPWA 0–range fit (sol. B)
1421
MARTIN
70 RVUE Constant K-matrix
1416 ± 4
MARTIN
69 HBC
Constant K-matrix
1403 ± 3
KIM
67 HBC
K-matrix fit
41407.5± 1.2
KITTEL
66 HBC
0–effective-range fit
1410.7± 1.0
KIM
65 HBC
0–effective-range fit
4 SAKITT
1409.6± 1.7
65 HBC
0–effective-range fit
1 The KIMURA 00 values are from fits A and B from a coupled-channel potential model using low-energy K N and Σ π data, kaonic-hydrogen x-ray measurements, and our Λ(1405)
mass and width. The results bear mainly on the nature of the Λ(1405): three-quark stateor K N bound state.
2 The MARTIN 81 fit includes the K ± p forward scattering amplitudes and the dispersion
relations they must satisfy.
3 See also the accompanying paper of THOMAS 73.
4 Data of SAKITT 65 are used in the fit by KITTEL 66.

https://pdg.lbl.gov

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Citation: S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)Λ(1405) WIDTHPRODUCTION EXPERIMENTS
VALUE (MeV)EVTS

DOCUMENT ID

TECNCOMMENT50.5± 2.0 OUR AVERAGE
62 ± 10HASSANVAND 13 SPEC p p → p Λ(1405) K +150 ± 2DALITZ
91
M-matrix fit• • • We do not use the following data for averages, fits, limits, etc. • • •424 +ESMAILI
10 RVUE 4 He K − → Σ ± π ∓ X at rest
− 31 HEMINGWAY 85 HBC
32 ± 1700
K − p 4.2 GeV/c245 to 55
400
THOMAS
73 HBCπ − p 1.69 GeV/c35120
BARBARO-... 68B DBC
K − d 2.1–2.7 GeV/c
50 ± 1067
BIRMINGHAM 66 HBC
K − p 3.5 GeV/c89 ± 20
ENGLER
65 HDBC
60 ± 20MUSGRAVE
65 HBC
35 ± 5ALEXANDER 62 HBC
50
ALSTON
62 HBC
20
ALSTON61B HBC
1 DALITZ 91 fits the HEMINGWAY 85 data.
2 THOMAS 73 data is fit by CHAO 73 (see next section).

EXTRAPOLATIONS BELOW N K THRESHOLD
VALUE (MeV)

DOCUMENT ID

TECNCOMMENT• • • We do not use the following data for averages, fits, limits, etc. • • •1 KIMURA
50.24 or 50.26
00
potential model
2 MARTIN
3081K-matrix fit
3,4 CHAO
55
73 DPWA 0–range fit (sol. B)
20
MARTIN
70 RVUE Constant K-matrix
29 ± 6MARTIN
69 HBCConstant K-matrix
50 ± 5KIM
67 HBCK-matrix fit
5 KITTEL
34.1± 4.1
66 HBC37.0± 3.2
KIM
65 HBC
5 SAKITT28.2± 4.1
65 HBC
1 The KIMURA 00 values are from fits A and B from a coupled-channel potential model using low-energy K N and Σ π data, kaonic-hydrogen x-ray measurements, and our Λ(1405)
mass and width. The results bear mainly on the nature of the Λ(1405): three-quark stateor K N bound state.
2 The MARTIN 81 fit includes the K ± p forward scattering amplitudes and the dispersion
relations they must satisfy.
3 An asymmetric shape, with Γ/2 = 41 MeV below resonance, 14 MeV above.
4 See also the accompanying paper of THOMAS 73.
5 Data of SAKITT 65 are used in the fit by KITTEL 66.

Λ(1405) DECAY MODES

Γ1
Γ2
Γ3
Γ4

ModeFraction (Γi /Γ)

Σπ
Λγ
Σ0γ
NK100 %

https://pdg.lbl.gov

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Citation: S. Navas et al. (Particle Data Group), Phys. Rev. D 110, 030001 (2024)Λ(1405) PARTIAL WIDTHS
Γ Λγ

Γ2

VALUE (keV)

DOCUMENT ID

COMMENT• • • We do not use the following data for averages, fits, limits, etc. • • •27± 8

BURKHARDT 91

Isobar model fit

DOCUMENT ID

COMMENT


Γ Σ0γ

Γ3

VALUE (keV)• • • We do not use the following data for averages, fits, limits, etc. • • •10 ± 4 or 23 ± 7

BURKHARDT 91

Isobar model fit

Λ(1405) BRANCHING RATIOSΓ N K /Γ Σ π
VALUEΓ4 /Γ1CL%

DOCUMENT ID

TECNCOMMENT• • • We do not use the following data for averages, fits, limits, etc. • • •<395
HEMINGWAY 85 HBC
K − p 4.2 GeV/cΛ(1405) REFERENCES
AIKAWA
23
MAI
15
MORIYA
14GUO
13
HASSANVAND 13Also
IKEDA
12
ESMAILI
10KIMURA
00
PDG
98
BURKHARDT 91
DALITZ91
HEMINGWAY 85
MARTIN
81
CHAO
73
THOMAS73
MARTIN70
MARTIN69
Also
BARBARO-... 68B
KIM
67
BIRMINGHAM 66
KITTEL
66
ENGLER
65
KIM
65
MUSGRAVE
65
SAKITT65
ALEXANDER 62
ALSTON62
ALSTON61B

PL B837 137637
EPJ A51 30
PRL 112 082004
PR C87 035202
PR C87 055202
PR C88 019905 (errat.)
NP A881 98
PL B686 23
PR C62 015206
EPJ C3 1
PR C44 607
JP G17 289
NP B253 742
NP B179 33
NP B56 46
NP B56 15
NP B16 479
PR 183 1352
PR 183 1345
PRL 21 573
PRL 19 1074
PR 152 1148
PL 21 349
PRL 15 224
PRL 14 29
NC 35 735
PR 139 B719
PRL 8 447
CERN Conf. 311
PRL 6 698

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M. Hassanvand et al.
Y. Ikeda, T. Hyodo, W. Weise(TUM, RIKEN, TINT)
J. Esmaili, Y. Akaishi, T. Yamazaki(RIKEN, ISUT+)
M. Kimura et al.
C. Caso et al.
(PDG Collab.)
H. Burkhardt, J. Lowe
(NOTT, UNM, BIRM)
R.H. Dalitz, A. Deloff(OXFTP, WINR)
R.J. Hemingway(CERN) J
A.D. Martin(DURH)
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(RHEL, CMU, LOUC)
D.W. Thomas et al.
(CMU) J
A.D. Martin, G.G. Ross(DURH)
B.R. Martin, M. Sakitt(LOUC, BNL)
B.R. Martin, M. Sakitt(LOUC, BNL)
A. Barbaro-Galtieri et al.
(LRL, SLAC)
J.K. Kim(YALE)
M. Haque et al.
(BIRM, GLAS, LOIC, OXF+)
W. Kittel, G. Otter, I. Wacek(VIEN)
A. Engler et al.
(CMU, BNL) IJ
J.K. Kim(COLU)
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(BIRM, CERN, EPOL+)
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(UMD, LRL)
G. Alexander et al.
(LRL) I
M.H. Alston et al.
(LRL) I
M.H. Alston et al.
(LRL) IOTHER RELATED PAPERS
IWASAKI97
FINK90LEINWEBER 90
MUELLER-GR... 90
BARRETT89
BATTY89

PRL 78 3067
PR C41 2720
ANP 198 203
NP A513 557
NC 102A 179
NC 102A 255

https://pdg.lbl.gov

M. Iwasaki et al.
(KEK 228 Collab.)
P.J.Jr. Fink et al.
(IBMY, ORST, ANSM)
D.B. Leinweber(MCMS)
A. Mueller-Groeling, K. Holinde, J. Speth(JULI)
R.C. Barrett(SURR)
C.J. Batty, A. Gal(RAL, HEBR)

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

CAPSTICK89
Excited Baryons 88, p.32 S. Capstick(GUEL)LOWE
89
NC 102A 167
J. Lowe(BIRM)WHITEHOUSE 89
PRL 63 1352
D.A. Whitehouse et al.
(BIRM, BOST, BRCO+)SIEGEL88
PR C38 2221
P.B. Siegel, W. Weise(REGE)
WORKMAN88
PR D37 3117
R.L. Workman, H.W. Fearing(TRIU)SCHNICK87
PRL 58 1719
J. Schnick, R.H. Landau(ORST)CAPSTICK86
PR D34 2809
S. Capstick, N. Isgur(TNTO)JENNINGS86
PL B176 229
B.K. Jennings(TRIU)
MALTMAN86
PR D34 1372
K. Maltman, N. Isgur(LANL, TNTO)
ZHONG
86PL B171 471
Y.S. Zhong et al.
(ADLD, TRIU, SURR)
BURKHARDT 85
NP A440 653
H. Burkhardt, J. Lowe, A.S. Rosenthal(NOTT+)DAREWYCH85
PR D32 1765
J.W. Darewych, R. Koniuk, N. Isgur (YORKC, TNTO)
VEIT
85
PR D31 1033
E.A. Veit et al.
(TRIU, ADLD, SURR)
KIANG
84
PR C30 1638
D. Kiang et al.
(DALH, MCMS)MILLER
84
Conference paper
D.J. Miller(LOUC)
Conf. Intersections between Particle and Nuclear Physics, p. 783
VANDIJK84
PR D30 937
W. van Dijk
(MCMS)
VEIT
84
PL 137B 415
E.A. Veit et al.
(TRIU, SURR, CERN)DALITZ
82
Heid. Conf.
R.H. Dalitz et al.
(OXFTP)
Heidelberg Conf., p. 201
DALITZ
81
Kaon Conf.
R.H. Dalitz, J.G. McGinley(OXFTP)
Low and Intermediate Energy Kaon-Nucleon Physics, p.381
MARTIN81B Kaon Conf.
A.D. Martin(DURH)
Low and Intermediate Energy Kaon-Nucelon Physics, p. 97
OADES77
NC 42A 462
G.C. Oades, G. Rasche(AARH, ZURI)
SHAW
73
Purdue Conf. 417
G.L. Shaw(UCI)
BARBARO-... 72
LBL-555
A. Barbaro-Galtieri(LBL)
DOBSON72
PR D6 3256
P.N. Dobson, R. McElhaney(HAWA)RAJASEKA... 72
PR D5 610
G. Rajasekaran(TATA)
Earlier papers also cited in RAJASEKARAN 72.
CLINE71
PRL 26 1194
D. Cline, R. Laumann, J. Mapp
(WISC)MARTIN71
PL 35B 62
A.D. Martin, A.D. Martin, G.G. Ross (DURH, LOUC+)DALITZ67
PR 153 1617
R.H. Dalitz, T.C. Wong, G. Rajasekaran(OXFTP+)DONALD66
PL 22 711
R.A. Donald et al.
(LIVP)KADYK66
PRL 17 599
J.A. Kadyk et al.
(LRL)
ABRAMS65
PR 139 B454
G.S. Abrams, B. Sechi-Zorn(UMD)

https://pdg.lbl.gov

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