Σ+ and Σ-Polarization in the J/ψ and ψ3686 Decays

Date Issued
31-07-2020
Author(s)
Ablikim, M.
Achasov, M. N.
Adlarson, P.
Ahmed, S.
Albrecht, M.
Amoroso, A.
An, Q.
Anita,
Bai, Y.
Bakina, O.
Ferroli, R. Baldini
Balossino, I.
Ban, Y.
Begzsuren, K.
Bennett, J. V.
Berger, N.
Bertani, M.
Bettoni, D.
Bianchi, F.
Biernat, J.
Bloms, J.
Bortone, A.
Boyko, I.
Briere, R. A.
Cai, H.
Cai, X.
Calcaterra, A.
Cao, G. F.
Cao, N.
Cetin, S. A.
Chang, J. F.
Chang, W. L.
Chelkov, G.
Chen, D. Y.
Chen, G.
Chen, H. S.
Chen, M. L.
Chen, S. J.
Chen, X. R.
Chen, Y. B.
Cheng, W.
Cibinetto, G.
Cossio, F.
Cui, X. F.
Dai, H. L.
Dai, J. P.
Dai, X. C.
Dbeyssi, A.
De Boer, R. B.
Dedovich, D.
Deng, Z. Y.
Denig, A.
Denysenko, I.
Destefanis, M.
De Mori, F.
Ding, Y.
Dong, C.
Dong, J.
Dong, L. Y.
Dong, M. Y.
Du, S. X.
Fang, J.
Fang, S. S.
Fang, Y.
Farinelli, R.
Fava, L.
Feldbauer, F.
Felici, G.
Feng, C. Q.
Fritsch, M.
Fu, C. D.
Fu, Y.
Gao, X. L.
Gao, Y.
Gao, Y.
Gao, Y. G.
Garzia, I.
Gersabeck, E. M.
Gilman, A.
Goetzen, K.
Gong, L.
Gong, W. X.
Gradl, W.
Greco, M.
Gu, L. M.
Gu, M. H.
Gu, S.
Gu, Y. T.
Guan, C. Y.
Guo, A. Q.
Guo, L. B.
Guo, R. P.
Guo, Y. P.
Guo, Y. P.
Guskov, A.
Han, S.
Han, T. T.
Han, T. Z.
Hao, X. Q.
Harris, F. A.
DOI
Abstract
From 1310.6×106 J/ψ and 448.1×106 ψ(3686) events collected with the BESIII experiment, we report the first observation of ς+ and ς¯-spin polarization in e+e-→J/ψ[ψ(3686)]→ς+ς¯-decays. The relative phases of the form factors Δφ have been measured to be (-15.5±0.7±0.5)° and (21.7±4.0±0.8)° with J/ψ and ψ(3686) data, respectively. The nonzero value of Δφ allows for a direct and simultaneous measurement of the decay asymmetry parameters of ς+→pπ0(α0=-0.998±0.037±0.009) and ς¯-→p¯π0(α¯0=0.990±0.037±0.011), the latter value being determined for the first time. The average decay asymmetry, (α0-α¯0)/2, is calculated to be-0.994±0.004±0.002. The CP asymmetry ACP,ς=(α0+α¯0)/(α0-α¯0)=-0.004±0.037±0.010 is extracted for the first time, and is found to be consistent with CP conservation.
Volume
125