Precision <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>C</mml:mi> <mml:mi>P</mml:mi> </mml:math> Symmetry Test and Polarization Analysis in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msup> <mml:mi mathvariant="normal">Σ</mml:mi> <mml:mo>+</mml:mo> </mml:msup> </mml:math> Decays
M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Qi An, Yunfei Bai, O. Bakina, Y. Ban, H.-R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, Minghui Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, X. Y. Chai, J. F. Chang, G. R., Y. Z., G. Chelkov, C. Chen, C. H. Chen, Chao Chen, G. Chen, H. S. Chen, H. Y. Chen, M. L. Chen, S. Chen, S. L. Chen, Shaomin Chen, T. Chen, Xiaoyan Chen, X. T. Chen, Y. B. Chen, Y. Q. Chen, Z. J. Chen, Z. K. Chen, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, Dmitri Dedovich, C. Q. Deng, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, B. Ding, X. X. Ding, Y. Ding, Y. X. Ding, Y. X. Ding, J. Dong, L. Y. Dong, M. Y. Dong, Xiang-Kun Dong, M. C. Du, S. X. Du, Y. Y. Duan, Z. H. Duan, P. Egorov, Gaofeng Fan, J. J. Fan, Yanhui Fan, J. Fang, J. Fang, S. S. Fang, W. X. Fang, Yong Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, Jianghe Feng, Y. T. Feng, M. Fritsch, C. D. Fu, J. Fu
Abstract
A stringent test of CP symmetry in hyperon decays is performed using 1.0×10^{10} J/ψ events and 2.7×10^{9} ψ(3686) events collected by the BESIII experiment. The CP asymmetry in the two-body nonleptonic weak decays Σ^{+}→pπ^{0} and Σ[over ¯]^{-}→p[over ¯]π^{0} is determined to be A_{CP}=-0.0118±0.0083(stat)±0.0028(syst), consistent with CP conservation. The average decay parameter ⟨α_{0}⟩=-0.9869±0.0011(stat)±0.0016(syst) represents the most precise measurement in the baryon sector to date. A model-independent analysis of the hyperon polarization is performed for the first time at J/ψ and ψ(3686) resonances, revealing a clear sign reversal and offering new insight into SU(3) symmetry breaking and baryon internal structure. These results provide the most stringent constraints on CP violation in Σ decays and establish a benchmark for future precision studies.