Citation: P.A. Zyla et al. (Particle Data Group), Prog. Theor. Exp. Phys. 2020, 083C01 (2020) Ξ BARYONS (S = −2, I = 1/2) Ξ 0 = uss, Ξ − = dss 0 P 1 1 + Ξ I (J ) = 2 ( 2 ) P is not yet measured; + is the quark model prediction. Mass m = 1314.86 ± 0.20 MeV mΞ − − mΞ 0 = 6.85 ± 0.21 MeV Mean life τ = (2.90 ± 0.09) × 10−10 s cτ = 8.71 cm Magnetic moment µ = −1.250 ± 0.014 µN Decay parameters Λπ0 α = −0.356 ± 0.011 " φ = (21 ± 12)◦ " γ = 0.85 [a] " +12 ◦ [a] ∆ = (218−19) Λγ α = −0.70 ± 0.07 Λe+ e− α = −0.8 ± 0.2 Σ 0 γ α = −0.69 ± 0.06 + − Σ e νe g1(0)/f1(0) = 1.22 ± 0.05 + − Σ e νe f2(0)/f1(0) = 2.0 ± 0.9 p 0 Ξ DECAY MODES Fraction (Γi /Γ) Confidence level (MeV/c) Λπ0 (99.524±0.012) % 135 − Λγ ( 1.17 ±0.07 ) × 10 3 184 − − Λe+ e ( 7.6 ±0.6 ) × 10 6 184 − Σ 0 γ ( 3.33 ±0.10 ) × 10 3 117 + − −4 Σ e νe ( 2.52 ±0.08 ) × 10 120 + − −6 Σ µ νµ ( 2.33 ±0.35 ) × 10 64 ∆S = ∆Q (SQ) violating modes or ∆S = 2 forbidden (S2) modes − + −4 Σ e νe SQ < 9 × 10 90% 112 − + −4 Σ µ νµ SQ < 9 × 10 90% 49 − − p π S2 < 8 × 10 6 90% 299 − −3 p e νe S2 < 1.3 × 10 323 − −3 p µ νµ S2 < 1.3 × 10 309 HTTP://PDG.LBL.GOV Page1 Created: 6/1/2020 08:28 Citation: P.A. Zyla et al. (Particle Data Group), Prog. Theor. Exp. Phys. 2020, 083C01 (2020) − P 1 1 + Ξ I (J ) = 2 ( 2 ) P is not yet measured; + is the quark model prediction. Mass m = 1321.71 ± 0.07 MeV −5 (mΞ − − mΞ + ) / mΞ − = (−3 ± 9) × 10 Mean life τ = (1.639 ± 0.015) × 10−10 s cτ = 4.91 cm (τ Ξ − − τ Ξ + ) / τ Ξ − = −0.01 ± 0.07 Magnetic moment µ = −0.6507 ± 0.0025 µN (µ − + µ + ) / µ − = +0.01 ± 0.05 Ξ Ξ Ξ Decay parameters Λπ− α = −0.401 ± 0.010 − + −4 [α(Ξ )α−(Λ) − α(Ξ )α+(Λ)]/[sum ]=(0 ± 7) × 10 " φ = (−2.1 ± 0.8)◦ " γ = 0.89 [a] " ∆ = (175.9 ± 1.5)◦ [a] − [b] Λe νe gA/gV = −0.25 ± 0.05 p − Ξ DECAY MODES Fraction (Γi /Γ) Confidence level (MeV/c) − Λπ (99.887±0.035) % 140 − − Σ γ ( 1.27 ±0.23 ) × 10 4 118 − −4 Λe νe ( 5.63 ±0.31 ) × 10 190 − − . +3.5 × 4 Λµ νµ ( 3 5 −2.2 ) 10 163 0 − −5 Σ e νe ( 8.7 ±1.7 ) × 10 123 0 − −4 Σ µ νµ < 8 × 10 90% 70 0 − −3 Ξ e νe < 2.3 × 10 90% 7 ∆S = 2 forbidden (S2) modes − − nπ S2 < 1.9 × 10 5 90% 304 − −3 ne νe S2 < 3.2 × 10 90% 327 − nµ νµ S2 < 1.5 % 90% 314 − − − p π π S2 < 4 × 10 4 90% 223 − − −4 p π e νe S2 < 4 × 10 90% 305 − − −4 p π µ νµ S2 < 4 × 10 90% 251 − − − p µ µ L < 4 × 10 8 90% 272 Ξ + P 1 3 + (1530) 3/2 I (J ) = 2 ( 2 ) Ξ (1530)0 mass m = 1531.80 ± 0.32MeV (S= 1.3) − Ξ (1530) mass m = 1535.0 ± 0.6 MeV Ξ (1530)0 full width Γ = 9.1 ± 0.5 MeV − +1.7 Ξ (1530) full width Γ = 9.9−1.9 MeV HTTP://PDG.LBL.GOV Page2 Created: 6/1/2020 08:28 Citation: P.A. Zyla et al. (Particle Data Group), Prog. Theor. Exp. Phys. 2020, 083C01 (2020) p Ξ(1530) DECAY MODES Fraction (Γi /Γ) Confidence level (MeV/c) Ξ π 100 % 158 Ξ γ <3.7 % 90% 202 Ξ P 1 ? (1690) I (J ) = 2 (? ) Mass m = 1690 ± 10 MeV [c] Full width Γ < 30 MeV Ξ(1690) DECAY MODES Fraction (Γi /Γ) p (MeV/c) ΛK seen 240 Σ K seen 70 Ξ π seen 311 − − Ξ π+ π possibly seen 213 Ξ − P 1 3 − (1820) 3/2 I (J ) = 2 ( 2 ) Mass m = 1823 ± 5 MeV [c] +15 [c] Full width Γ = 24−10 MeV Ξ(1820) DECAY MODES Fraction (Γi /Γ) p (MeV/c) ΛK large 402 Σ K small 324 Ξ π small 421 Ξ (1530)π small 237 Ξ P 1 ? (1950) I (J ) = 2 (? ) Mass m = 1950 ± 15 MeV [c] Full width Γ = 60 ± 20 MeV [c] Ξ(1950) DECAY MODES Fraction (Γi /Γ) p (MeV/c) ΛK seen 522 Σ K possibly seen 460 Ξ π seen 519 HTTP://PDG.LBL.GOV Page3 Created: 6/1/2020 08:28 Citation: P.A. Zyla et al. (Particle Data Group), Prog. Theor. Exp. Phys. 2020, 083C01 (2020) Ξ P 1 ≥ 5 ? (2030) I (J ) = 2 ( 2 ) Mass m = 2025 ± 5 MeV [c] +15 [c] Full width Γ = 20− 5 MeV Ξ(2030) DECAY MODES Fraction (Γi /Γ) p (MeV/c) ΛK ∼ 20 % 585 Σ K ∼ 80 % 529 Ξ π small 574 Ξ (1530)π small 416 ΛK π small 499 Σ K π small 428 NOTES [a] The decay parameters γ and ∆ are calculated from α and φ using 2 1 2 γ = p1−α cosφ , tan∆ = −α p1−α sinφ . See the “Note on Baryon Decay Parameters” in the neutron Particle List- ings. [b] The parameters gA, gV , and gWM for semileptonic modes are defined by B γ g g γ i g m σ qν B φ f [ λ( V + A 5) + ( WM / Bi ) λν ] i , and AV is defined by g /g = g /g eiφAV . See the “Note on Baryon Decay Parameters” A V A V in the neutron Particle Listings. [c] Our estimate. See the Particle Listings for details. HTTP://PDG.LBL.GOV Page4 Created: 6/1/2020 08:28.