Helicity Amplitude Analysis of e^＋e^- ψ（2S） → γχcJ→γ∧∧^-→γpπ^-p^-π^＋＊

An analysis of the helicity amplitude is performed on the process e^＋e^- ψ（2S） → γχcJ→γ∧∧^-→γpπ^-p^-π^＋. The joint angular distributions for each decay chain are given, and we focus on discussing the E1 contributions to ψ（2S） radiative decays, and the violation of the helicity selection rule in χcJ decays into hyperon pairs, together with the possibility of observing parity violation in successive hyperon decays.     

Prospects on Determining Electric Dipole Moments of ∑ and Hyperons at BESⅢ

The electric dipole moment of ∑（or ） hyperon, d∑ （or d ）, can be detected by analyzing the angular distribution in the decay process of J/φ → ∑^0^-∑^0（ ）. The dependence of d∑ （or d ） on the free parameters describing the angular distribution is studied in detail with a Monte Carlo simulation based on 10^9 J/φ events expected in one year data taking at BESⅢ. The result shows that an expected upper limit with 10^-16 ,- 10^-18 ecru on d∑ （or d ） can be achieved depending on the true values of free parameters.