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Σ+ and Σ¯ Polarization in the J/ψ and ψ(3686) Decays

M. Ablikim et al. (BESIII Collaboration)
Phys. Rev. Lett. 125, 052004 – Published 31 July 2020
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Abstract

From 1310.6×106J/ψ and 448.1×106ψ(3686) events collected with the BESIII experiment, we report the first observation of Σ+ and Σ¯ spin polarization in e+eJ/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, (α0α¯0)/2, is calculated to be 0.994±0.004±0.002. The CP asymmetry ACP,Σ=(α0+α¯0)/(α0α¯0)=0.004±0.037±0.010 is extracted for the first time, and is found to be consistent with CP conservation.

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  • Received 17 April 2020
  • Accepted 18 June 2020

DOI:https://doi.org/10.1103/PhysRevLett.125.052004

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

Published by the American Physical Society

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Vol. 125, Iss. 5 — 31 July 2020

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