2025/03/21 by BESIII Collaboration, Ablikim, M., Achasov, M. N. +678
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex)
paper · doi:10.48550/arxiv.2503.17165
The non-leptonic two-body weak decays Σ+ → p π0 and Σ- → p π0 are investigated, utilizing (1.0087±0.0044)×1010 J/ψ events and (2.7124±0.0143)×109 ψ(3686) events collected by BESIII experiment. The precision of the weak-decay parameters for the decays Σ+ → p π0 (α0) and Σ- → p π0 (α0) is improved by a factor of three compared to the previous world average. Furthermore, the quantum-entangled Σ+Σ- system enables the most precise test of CP symmetry for the decay Σ+→ pπ0, through the asymmetry observable ACP=(α0+α0)/(α0-α0) that is measured to be -0.0118±0.0083\rm stat±0.0028\rm syst. Assuming CP conservation, the average decay parameter is determined to be < α\rm 0> = (α0-α0)/2=-0.9869±0.0011\rm stat±0.0016\rm syst, which is the most precise measurement of the asymmetry decay parameters in baryon sectors. The angular dependence of the ratio of the polarization of the Σ+ in both J/ψ and ψ(3686) decays is studied for the first time.