Measurement of the Matrix Element for the Decay ${\eta }^{\prime }\to \eta {\pi }^{+}{\pi }^{-}$

Abstract

The Dalitz plot of ${\eta }^{\prime }\to \eta {\pi }^{+}{\pi }^{-}$ decay is studied using $(225.2\pm 2.8)\times 10^6$ $\text{jpsi}$ events collected with the BESIII detector at the BEPCII $e^{+}{e}^{-}$ collider. With the largest sample of ${\eta }^{\prime }$ decays to date, the parameters of the Dalitz plot are determined in a generalized and a linear representation. Also the branching fraction of $\text{jpsi}\to \gamma {\eta }^{\prime }$ is determined to be $(4.84\pm 0.03\pm 0.24)\times 10^{-3}$, where the first error is statistical and the second systematic.

Comments: 20 pages, 5 figures, published in PRD