Using (10087±44)×106 J/ψ events collected with the BESIII detector, numerous Ξ- and Λ decay asymmetry parameters are simultaneously determined from the process J/ψ→Ξ-Ξ¯+→Λ(pπ-)π-Λ¯(n¯π0)π+ and its charge-conjugate channel. The precisions of αΛ0 for Λ→nπ0 and α¯Λ0 for Λ¯→n¯π0 compared to world averages are improved by factors of 4 and 1.7, respectively. The ratio of decay asymmetry parameters of Λ → nπ0 to that of Λ → pπ−, hαΛ0i=hαΛ−i, is determined to be 0.873  0.012þ0.011, where the first and the second uncertainties are statistical and systematic, respectively. −0.010 The ratio is smaller than unity more than 5σ, which signifies the existence of the ΔI 1⁄4 3=2 transition in Λ for the first time. Besides, we test for CP symmetry in Ξ− → Λπ− and in Λ → nπ0 with the best precision to date.
Investigation of the Δi=1/2 Rule and Test of CP Symmetry through the Measurement of Decay Asymmetry Parameters in Ξ- Decays
Garzia, I.;Gramigna, S.;
2024
Abstract
Using (10087±44)×106 J/ψ events collected with the BESIII detector, numerous Ξ- and Λ decay asymmetry parameters are simultaneously determined from the process J/ψ→Ξ-Ξ¯+→Λ(pπ-)π-Λ¯(n¯π0)π+ and its charge-conjugate channel. The precisions of αΛ0 for Λ→nπ0 and α¯Λ0 for Λ¯→n¯π0 compared to world averages are improved by factors of 4 and 1.7, respectively. The ratio of decay asymmetry parameters of Λ → nπ0 to that of Λ → pπ−, hαΛ0i=hαΛ−i, is determined to be 0.873 0.012þ0.011, where the first and the second uncertainties are statistical and systematic, respectively. −0.010 The ratio is smaller than unity more than 5σ, which signifies the existence of the ΔI 1⁄4 3=2 transition in Λ for the first time. Besides, we test for CP symmetry in Ξ− → Λπ− and in Λ → nπ0 with the best precision to date.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
