Precision Study of ${\eta }^{\prime }\to \gamma {\pi }^{+}{\pi }^{-}$ Decay Dynamics

BESIII Collaboration, M. Ablikim, M. N. Achasov +431

Using a low background data sample of $9.7\times 10^5$ $J\psi \to \gamma {\eta }^{\prime }$, ${\eta }^{\prime }\to \gamma {\pi }^{+}{\pi }^{-}$ events, which are 2 orders of magnitude larger than those from the pr…