Precision Measurement of the Decay Σ^{+}→pγ in the Process J/ψ→Σ^{+}Σ[over ¯]^{-}

• Published in: Physical review letters 2023-05, Vol.130 (21), p.211901-211901, Article 211901
• Main Authors: Ablikim, M, Achasov, M N, Adlarson, P, Aliberti, R, Amoroso, A, An, M R, An, Q, Bai, Y, Bakina, O, Balossino, I, Ban, Y, Batozskaya, V, Begzsuren, K, Berger, N, Bertani, M, Bettoni, D, Bianchi, F, Bianco, E, Bloms, J, Bortone, A, Boyko, I, Briere, R A, Brueggemann, A, Cai, H, Cai, X, Calcaterra, A, Cao, G F, Cao, N, Cetin, S A, Chang, J F, Chang, T T, Chang, W L, Che, G R, Chelkov, G, Chen, C, Chen, Chao, Chen, G, Chen, H S, Chen, M L, Chen, S J, Chen, S M, Chen, T, Chen, X R, Chen, X T, Chen, Y B, Chen, Y Q, Chen, Z J, Cheng, W S, Choi, S K, Chu, X, Cibinetto, G, Coen, S C, Cossio, F, Cui, J J, Dai, H L, Dai, J P, Dbeyssi, A, de Boer, R E, Dedovich, D, Deng, Z Y, Denig, A, Denysenko, I, Destefanis, M, De Mori, F, Ding, B, Ding, X X, Ding, Y, Dong, J, Dong, L Y, Dong, M Y, Dong, X, Du, S X, Duan, Z H, Egorov, P, Fan, Y L, Fang, J, Fang, S S, Fang, W X, Fang, Y, Farinelli, R, Fava, L, Feldbauer, F, Felici, G, Feng, C Q, Feng, J H, Fischer, K, Fritsch, M, Fritzsch, C, Fu, C D, Fu, Y W, Gao, H, Gao, Y N, Gao, Yang, Garbolino, S, Garzia, I, Ge, P T, Ge, Z W, Geng, C, Gersabeck, E M
• Format: Article
• Language: English
• Subjects: Physics
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.130.211901

Using (10 087±44)×10^{6} J/ψ events collected with the BESIII detector, the radiative hyperon decay Σ^{+}→pγ is studied at an electron-positron collider experiment for the first time. The absolute branching fraction is measured to be (0.996±0.021_{stat}±0.018_{syst})×10^{-3}, which is lower than its world average value by 4.2 standard deviations. Its decay asymmetry parameter is determined to be -0.652±0.056_{stat}±0.020_{syst}. The branching fraction and decay asymmetry parameter are the most precise to date, and the accuracies are improved by 78% and 34%, respectively.