Production of $\sigma$ in $\psi (2S)\to {\pi }^{+}{\pi }^{-}J/\psi$

BES Collaboration, M. Ablikim

Using 14M $\psi (2S)$ events accumulated by BESII at the BEPC, a Covariant Helicity Amplitude Analysis is performed for $\psi (2S)\to {\pi }^{+}{\pi }^{-}J/\psi ,J/\psi \to {\mu }^{+}{\mu }^{-}$. The ${\pi }^{+}{\pi }^{-}$ mass spectrum,…