Ablikim, M.Achasov, M. N.Adlarson, P.Ai, X. C.Aliberti, R.Amoroso, A.Çetin, Serkant Ali2024-05-192024-05-1920230031-90071079-7114https://doi.org10.1103/PhysRevLett.131.191802https://hdl.handle.net/20.500.12713/5870The quantum entangled J/psi -> Sigma(+)(Sigma) over bar (-) pairs from (1.0087 +/- 0.0044) x 10(10) J/psi events taken by the BESIII detector are used to study the nonleptonic two-body weak decays Sigma(+) -> n pi(+) and (Sigma) over bar (-) -> (n) over bar pi(-). The CP-odd weak decay parameters of the decays Sigma(+) -> n pi(+) (alpha(+)) and (Sigma) over bar (-) -> (n) over bar pi(-) ((alpha) over bar (-)) are determined to be 0.0481 +/- 0.0031(stat) +/- 0.0019(syst) and -0.0565 +/- 0.0047(sta)t +/- 0.0022(syst), respectively. The decay parameter (alpha) over bar (-) is measured for the first time, and the accuracy of alpha(+) is improved by a factor of 4 compared to the previous results. The simultaneously determined decay parameters allow the first precision CP symmetry test for any hyperon decay with a neutron in the final state with the measurement of A(CP) = (alpha(+) + (alpha) over bar-)/(alpha(+) - (alpha) over bar (-))/2 = -0.080 +/- 0.052(stat) +/- 0.028(sys)t. Assuming CP conservation, the average decay parameter is determined as = (alpha(+) - (alpha) over bar (-))/2 = -0.0506 +/- 0.0026(stat) +/- 0.0019(syst), while the ratios alpha(+)/alpha(0) and (alpha) over bar (-)/(alpha) over bar (0) are -0.0490 +/- 0.0032(stat) +/- 0.0021(syst) and -0.0571 +/- 0.0053(stat) +/- 0.0032(syst), where alpha(0) and (alpha) over bar (0) are the decay parameters of the decays Sigma(+) -> p pi(0) and (Sigma) over bar (-) -> (p) over bar pi(0), respectively.eninfo:eu-repo/semantics/openAccessSigmaArticle1311938000397WOS:0011733529000022-s2.0-85177768607N/A10.1103/PhysRevLett.131.191802Q1