2020/04/17 by BESIII Collaboration, M. Ablikim, М. Н. Ачасов +492 · 68 citations
Chemistry · Physics and Astronomy · #Advanced NMR Techniques and Applications #Atomic and Subatomic Physics Research #Computer science #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1103/physrevlett.125.052004
published in Physical Review Letters 125(5), 052004 (American Physical Society)
arxiv created 2020/04/17 · openalex created_date 2020/04/24 · openalex publication_date 2020/07/31 · arxiv updated 2020/08/12 · openalex updated_date 2026/08/05
From 1310.6\ifmmode×\else\texttimes\fi106 J/\ensuremathψ and 448.1\ifmmode×\else\texttimes\fi106 \ensuremathψ(3686) events collected with the BESIII experiment, we report the first observation of \mathrm\ensuremathΣ+ and \mathrm\ensuremathΣ^\ensuremath- spin polarization in e+e^\ensuremath-\ensuremath→J/\ensuremathψ[\ensuremathψ(3686)]\ensuremath→\mathrm\ensuremathΣ+\mathrm\ensuremathΣ^\ensuremath- decays. The relative phases of the form factors \mathrm\ensuremathΔ\mathrm\ensuremathΦ have been measured to be (\ensuremath-15.5\ifmmode±\else\textpm\fi0.7\ifmmode±\else\textpm\fi0.5)\ifmmode^∘\else\textdegree\fi and (21.7\ifmmode±\else\textpm\fi4.0\ifmmode±\else\textpm\fi0.8)\ifmmode^∘\else\textdegree\fi with J/\ensuremathψ and \ensuremathψ(3686) data, respectively. The nonzero value of \mathrm\ensuremathΔ\mathrm\ensuremathΦ allows for a direct and simultaneous measurement of the decay asymmetry parameters of \mathrm\ensuremathΣ+\ensuremath→p\ensuremathπ0(\ensuremathα0=\ensuremath-0.998\ifmmode±\else\textpm\fi0.037\ifmmode±\else\textpm\fi0.009) and \mathrm\ensuremathΣ^\ensuremath-\ensuremath→p\ensuremathπ0(\ensuremathα0=0.990\ifmmode±\else\textpm\fi0.037\ifmmode±\else\textpm\fi0.011), the latter value being determined for the first time. The average decay asymmetry, (\ensuremathα0\ensuremath-\ensuremathα0)/2, is calculated to be \ensuremath-0.994\ifmmode±\else\textpm\fi0.004\ifmmode±\else\textpm\fi0.002. The CP asymmetry A_CP,\mathrm\ensuremathΣ=(\ensuremathα0+\ensuremathα0)/(\ensuremathα0\ensuremath-\ensuremathα0)=\ensuremath-0.004\ifmmode±\else\textpm\fi0.037\ifmmode±\else\textpm\fi0.010 is extracted for the first time, and is found to be consistent with CP conservation.