Indeed. I would also like to share some very interesting information about Omega minus baryon decay modes:
Citation: W.-M. Yao et al. (Particle Data Group), J. Phys. G 33, 1 (2006) and 2007 partial update for edition 2008 (URL:
http://pdg.lbl.gov)
Ω− I (JP) = 0(32
+) Status: ∗∗∗∗
The unambiguous discovery in both production and decay was by
BARNES 64. The quantum numbers follow from the assignment
of the particle to the baryon decuplet. DEUTSCHMANN 78 and
BAUBILLIER 78 rule out J = 1/2 and find consistency with J =
3/2. AUBERT,BE 06 finds from the decay angular distributions of
Ξ0c
→ Ω−K+ and Ω0c
→ Ω−K+ that J = 3/2; this depends on
the spins of the Ξ0c
and Ω0c
being J = 1/2, their supposed values.
We have omitted some results that have been superseded by later
experiments. See our earlier editions.
Ω− MASS
The fit assumes the Ω− and Ω+ masses are the same, and averages them
together.
VALUE (MeV) EVTS DOCUMENT ID TECN COMMENT
1672....45±0....29 OUR FIIIIT
1672....43±0....32 OUR AVERAGE
1673 ±1 100 HARTOUNI 85 SPEC 80–280 GeV K0
LC
1673.0 ±0.8 41 BAUBILLIER 78 HBC 8.25 GeV/c K−p
1671.7 ±0.6 27 HEMINGWAY 78 HBC 4.2 GeV/c K−p
1673.4 ±1.7 4 1 DIBIANCA 75 DBC 4.9 GeV/c K−d
1673.3 ±1.0 3 PALMER 68 HBC K−p 4.6, 5 GeV/c
1671.8 ±0.8 3 SCHULTZ 68 HBC K−p 5.5 GeV/c
1674.2 ±1.6 5 SCOTTER 68 HBC K−p 6 GeV/c
1672.1 ±1.0 1 2 FRY 55 EMUL
• • • We do not use the following data for averages, fits, limits, etc. • • •
1671.43±0.78 13 3 DEUTSCH... 73 HBC K−p 10 GeV/c
1671.9 ±1.2 6 3 SPETH 69 HBC See DEUTSCHMANN 73
1673.0 ±8.0 1 ABRAMS 64 HBC → Ξ−π0
1670.6 ±1.0 1 2 FRY 55B EMUL
1615 1 4 EISENBERG 54 EMUL
1 DIBIANCA 75 gives a mass for each event. We quote the average.
2 The FRY 55 and FRY 55B events were identified as Ω− by ALVAREZ 73. The masses
assume decay to ΛK− at rest. For FRY 55B, decay from an atomic orbit could Doppler
shift the K− energy and the resulting Ω− mass by several MeV. This shift is negligible
for FRY 55 because the Ω decay is approximately perpendicular to its orbital velocity,
as is known because the Λ strikes the nucleus (L.Alvarez, private communication 1973).
We have calculated the error assuming that the orbital n is 4 or larger.
3 Excluded from the average; the Ω− lifetimes measured by the experiments differ significantly
from other measurements.
4 The EISENBERG 54 mass was calculated for decay in flight. ALVAREZ 73 has shown
that the Ω interacted with an Ag nucleus to give K−Ξ Ag.
HTTP://PDG.LBL.GOV Page 1 Created: 6/7/2007 11:42
Citation: W.-M. Yao et al. (Particle Data Group), J. Phys. G 33, 1 (2006) and 2007 partial update for edition 2008 (URL:
http://pdg.lbl.gov)
Ω+ MASS
The fit assumes the Ω− and Ω+ masses are the same, and averages them
together.
VALUE (MeV) EVTS DOCUMENT ID TECN COMMENT
1672....45±0....29 OUR FIIIIT
1672....5 ±0....7 OURAVERAGE
1672 ±1 72 HARTOUNI 85 SPEC 80–280 GeV K0
L C
1673.1 ±1.0 1 FIRESTONE 71B HBC 12 GeV/c K+d
(m Ω− − mΩ+) / mΩ−
A test of CPT invariance.
VALUE DOCUMENT ID TECN COMMENT
((((−1....44±7....98))))×10−5 CHAN 98 E756 p Be, 800 GeV
Ω− MEAN LIIIIFE
Measurements with an error > 0.1 × 10−10 s have been omitted. The
fit assumes the Ω− and Ω+ mean lives are the same, and averages them
together.
VALUE (10−10 s) EVTS DOCUMENT ID TECN COMMENT
0....821±0....011 OUR FIIIIT
0....821±0....011 OUR AVERAGE
0.817±0.013±0.018 6934 CHAN 98 E756 p Be, 800 GeV
0.811±0.037 1096 LUK 88 SPEC p Be 400 GeV
0.823±0.013 12k BOURQUIN 84 SPEC SPS hyperon beam
• • • We do not use the following data for averages, fits, limits, etc. • • •
0.822±0.028 2437 BOURQUIN 79B SPEC See BOURQUIN 84
Ω+ MEAN LIIIIFE
The fit assumes the Ω− and Ω+ mean lives are the same, and averages
them together.
VALUE (10−10 s) EVTS DOCUMENT ID TECN COMMENT
0....821±0....011 OUR FIIIIT
0....823±0....031±0....022 1801 CHAN 98 E756 p Be, 800 GeV
(τ Ω− − τ Ω+) / τ Ω−
A test of CPT invariance. Our calculation, from the preceding two data
blocks.
VALUE DOCUMENT ID
−0....002±0....040 OUR ESTIIIIMATE
HTTP://PDG.LBL.GOV Page 2 Created: 6/7/2007 11:42
Citation: W.-M. Yao et al. (Particle Data Group), J. Phys. G 33, 1 (2006) and 2007 partial update for edition 2008 (URL:
http://pdg.lbl.gov)
Ω− MAGNETIIIIC MOMENT
VALUE (μN) EVTS DOCUMENT ID TECN COMMENT
−2....02 ±0....05 OUR AVERAGE
−2.024±0.056 235k WALLACE 95 SPEC Ω− 300–550 GeV
−1.94 ±0.17 ±0.14 25k DIEHL 91 SPEC Spin-transfer production
Ω− DECAY MODES
Mode Fraction (Γi /Γ) Confidence level
Γ1 ΛK− (67.8±0.7) %
Γ2 Ξ0 π− (23.6±0.7) %
Γ3 Ξ−π0 ( 8.6±0.4) %
Γ4 Ξ−π+π− ( 4.3+3.4
−1.3) × 10−4
Γ5 Ξ(1530)0 π− ( 6.4+5.1
−2.0) × 10−4
Γ6 Ξ0 e−νe ( 5.6±2.8) × 10−3
Γ7 Ξ−γ < 4.6 × 10−4 90%
ΔS = 2 fffforrrrbiiiidden ((((S2)))) modessss
Γ8 Λπ− S2 < 2.9 × 10−6 90%
Ω− BRANCHIIIING RATIIIIOS
The BOURQUIN 84 values (which include results of BOURQUIN 79B, a
separate experiment) are much more accurate than any other results, and
so the other results have been omitted.
ΓΛK−/Γttttottttallll Γ1/Γ
VALUE EVTS DOCUMENT ID TECN COMMENT
0....678±0....007 14k BOURQUIN 84 SPEC SPS hyperon beam
• • • We do not use the following data for averages, fits, limits, etc. • • •
0.686±0.013 1920 BOURQUIN 79B SPEC See BOURQUIN 84
ΓΞ0π−/Γttttottttallll Γ2/Γ
VALUE EVTS DOCUMENT ID TECN COMMENT
0....236±0....007 1947 BOURQUIN 84 SPEC SPS hyperon beam
• • • We do not use the following data for averages, fits, limits, etc. • • •
0.234±0.013 317 BOURQUIN 79B SPEC See BOURQUIN 84
ΓΞ−π0/Γttttottttallll Γ3/Γ
VALUE EVTS DOCUMENT ID TECN COMMENT
0....086±0....004 759 BOURQUIN 84 SPEC SPS hyperon beam
• • • We do not use the following data for averages, fits, limits, etc. • • •
0.080±0.008 145 BOURQUIN 79B SPEC See BOURQUIN 84
HTTP://PDG.LBL.GOV Page 3 Created: 6/7/2007 11:42
Citation: W.-M. Yao et al. (Particle Data Group), J. Phys. G 33, 1 (2006) and 2007 partial update for edition 2008 (URL:
http://pdg.lbl.gov)
ΓΞ−π+π−/Γttttottttallll Γ4/Γ
VALUE (units 10−4) EVTS DOCUMENT ID TECN COMMENT
4.3−+4.3+3.4
−1.3
4 BOURQUIN 84 SPEC SPS hyperon beam
ΓΞ((((1530))))0π−/Γttttottttallll Γ5/Γ
VALUE (units 10−4) EVTS DOCUMENT ID TECN COMMENT
6.4−+6.4+5.1
−2.0
4 5 BOURQUIN 84 SPEC SPS hyperon beam
• • • We do not use the following data for averages, fits, limits, etc. • • •
∼ 20 1 BOURQUIN 79B SPEC See BOURQUIN 84
5 The same 4 events as in the previous mode, with the isospin factor to take into account
Ξ(1530)0 → Ξ0 π0 decays included.
ΓΞ0e−νeeee/Γttttottttallll Γ6/Γ
VALUE (units 10−3) EVTS DOCUMENT ID TECN COMMENT
5....6±2....8 14 BOURQUIN 84 SPEC SPS hyperon beam
• • • We do not use the following data for averages, fits, limits, etc. • • •
∼ 10 3 BOURQUIN 79B SPEC See BOURQUIN 84
ΓΞ−γ/Γttttottttallll Γ7/Γ
VALUE (units 10−4) CL% EVTS DOCUMENT ID TECN COMMENT
< 4....6 90 0 ALBUQUERQ...94 E761 Ω− 375 GeV
• • • We do not use the following data for averages, fits, limits, etc. • • •
<22 90 9 BOURQUIN 84 SPEC SPS hyperon beam
<31 90 0 BOURQUIN 79B SPEC See BOURQUIN 84
ΓΛπ−/Γttttottttallll Γ8/Γ
ΔS=2. Forbidden in first-order weak interaction.
VALUE (units 10−6) CL% DOCUMENT ID TECN COMMENT
< 2....9 90 WHITE 05 HYCP p Cu, 800 GeV
• • • We do not use the following data for averages, fits, limits, etc. • • •
< 190 90 BOURQUIN 84 SPEC SPS hyperon beam
<1300 90 BOURQUIN 79B SPEC See BOURQUIN 84
Ω− DECAY PARAMETERS
α FOR Ω− → ΛK−
Some early results have been omitted.
VALUE EVTS DOCUMENT ID TECN COMMENT
0....0180±0....0024 OUR AVERAGE
+0.0207±0.0051±0.0081 960k 6 CHEN 05 HYCP p Cu, 800 GeV
+0.0178±0.0019±0.0016 4.5M 6 LU 05A HYCP p Cu, 800 GeV
• • • We do not use the following data for averages, fits, limits, etc. • • •
−0.028 ±0.047 6953 CHAN 98 E756 p Be, 800 GeV
−0.034 ±0.079 1743 LUK 88 SPEC p Be 400 GeV
−0.025 ±0.028 12k BOURQUIN 84 SPEC SPS hyperon beam
6The results of CHEN 05 and LU 05A are from different experimental runs.
HTTP://PDG.LBL.GOV Page 4 Created: 6/7/2007 11:42
Citation: W.-M. Yao et al. (Particle Data Group), J. Phys. G 33, 1 (2006) and 2007 partial update for edition 2008 (URL:
http://pdg.lbl.gov)
α FOR Ω+ → ΛK+
VALUE EVTS DOCUMENT ID TECN COMMENT
−0....0181±0....0028±0....0026 1.89M LU 06 HYCP p Cu, 800 GeV
• • • We do not use the following data for averages, fits, limits, etc. • • •
+0.017 ±0.077 1823 CHAN 98 E756 p Be, 800 GeV
(α + α)/(α − α) in Ω− → ΛK−, Ω+ → ΛK+
Zero if CP is conserved.
VALUE DOCUMENT ID TECN COMMENT
−0....016±0....092±0....089 7 LU 06 HYCP p Cu, 800 GeV
7 This value uses the results of CHEN 05, LU 05A, and LU 06.
α FOR Ω− → Ξ0π−
VALUE EVTS DOCUMENT ID TECN COMMENT
+0....09±0....14 1630 BOURQUIN 84 SPEC SPS hyperon beam
α FOR Ω− → Ξ−π0
VALUE EVTS DOCUMENT ID TECN COMMENT
+0....05±0....21 614 BOURQUIN 84 SPEC SPS hyperon beam
Ω− REFERENCES
We have omitted some papers that have been superseded by later experiments.
See our earlier editions.
AUBERT,BE 06 PRL 97 112001 B. Aubert et al. (BABAR Collab.)
LU 06 PRL 96 242001 L.C. Lu et al. (FNAL HyperCP Collab.)
CHEN 05 PR D71 051102R Y.C. Chen et al. (FNAL HyperCP Collab.)
LU 05A PL B617 11 L.C. Lu et al. (FNAL HyperCP Collab.)
WHITE 05 PRL 94 101804 C.G. White et al. (FNAL HyperCP Collab.)
CHAN 98 PR D58 072002 A.W. Chan et al. (FNAL E756 Collab.)
WALLACE 95 PRL 74 3732 N.B. Wallace et al. (MINN, ARIZ, MICH+)
ALBUQUERQ... 94 PR D50 R18 I.F. Albuquerque et al. (FNAL E761 Collab.)
DIEHL 91 PRL 67 804 H.T. Diehl et al. (RUTG, FNAL, MICH+)
LUK 88 PR D38 19 K.B. Luk et al. (RUTG, WISC, MICH, MINN)
HARTOUNI 85 PRL 54 628 E.P. Hartouni et al. (COLU, ILL, FNAL)
BOURQUIN 84 NP B241 1 M.H. Bourquin et al. (BRIS, GEVA, HEIDP+)
Also PL 87B 297 M.H. Bourquin et al. (BRIS, GEVA, HEIDP+)
BOURQUIN 79B PL 88B 192 M.H. Bourquin et al. (BRIS, GEVA, HEIDP+)
BAUBILLIER 78 PL 78B 342 M. Baubillier et al. (BIRM, CERN, GLAS+) J
DEUTSCH... 78 PL 73B 96 M. Deutschmann et al. (AACH3, BERL, CERN+) J
HEMINGWAY 78 NP B142 205 R.J. Hemingway et al. (CERN, ZEEM, NIJM+)
DIBIANCA 75 NP B98 137 F.A. Dibianca, R.J. Endorf (CMU)
ALVAREZ 73 PR D8 702 L.W. Alvarez (LBL)
DEUTSCH... 73 NP B61 102 M. Deutschmann et al. (ABCLV Collab.)
FIRESTONE 71B PRL 26 410 I. Firestone et al. (LRL)
SPETH 69 PL 29B 252 R. Speth et al. (AACH, BERL, CERN, LOIC+)
PALMER 68 PL 26B 323 R.B. Palmer et al. (BNL, SYRA)
SCHULTZ 68 PR 168 1509 P.F. Schultz et al. (ILL, ANL, NWES+)
SCOTTER 68 PL 26B 474 D. Scotter et al. (BIRM, GLAS, LOIC+)
ABRAMS 64 PRL 13 670 G.S. Abrams et al. (UMD, NRL)
BARNES 64 PRL 12 204 V.E. Barnes et al. (BNL)
FRY 55 PR 97 1189 W.F. Fry, J. Schneps, M.S. Swami (WISC)
FRY 55B NC 2 346 W.F. Fry, J. Schneps, M.S. Swami (WISC)
EISENBERG 54 PR 96 541 Y. Eisenberg (CORN)