Investigation of the ΔI=1/2 Rule and Test of CP Symmetry through the Measurement of Decay Asymmetry Parameters in Ξ
Phys Rev Lett
; 132(10): 101801, 2024 Mar 08.
Article
em En
| MEDLINE
| ID: mdl-38518329
ABSTRACT
Using (10087±44)×10^{6} J/ψ events collected with the BESIII detector, numerous Ξ^{-} and Λ decay asymmetry parameters are simultaneously determined from the process J/ψâΞ^{-}Ξ[over ¯]^{+}âΛ(pπ^{-})π^{-}Λ[over ¯](n[over ¯]π^{0})π^{+} and its charge-conjugate channel. The precisions of α_{Λ0} for Λânπ^{0} and α[over ¯]_{Λ0} for Λ[over ¯]ân[over ¯]π^{0} compared to world averages are improved by factors of 4 and 1.7, respectively. The ratio of decay asymmetry parameters of Λânπ^{0} to that of Λâpπ^{-}, ⟨α_{Λ0}⟩/⟨α_{Λ-}⟩, is determined to be 0.873±0.012_{-0.010}^{+0.011}, where the first and the second uncertainties are statistical and systematic, respectively. The ratio is smaller than unity more than 5σ, which signifies the existence of the ΔI=3/2 transition in Λ for the first time. Besides, we test for CP symmetry in Ξ^{-}âΛπ^{-} and in Λânπ^{0} with the best precision to date.
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MEDLINE
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En
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Phys Rev Lett
Ano de publicação:
2024
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Article