Measurement of the Matrix Element for the Decay $η^{\prime} \to ηπ^+π^-$

Abstract

The Dalitz plot of $η^{\prime} \to ηπ^+ π^-$ decay is studied using $(225.2\pm2.8)\times 10^6$ $\jpsi$ events collected with the BESIII detector at the BEPCII $e^+e^-$ collider. With the largest sample of $η^{\prime}$ decays to date, the parameters of the Dalitz plot are determined in a generalized and a linear representation. Also the branching fraction of $\jpsi \to γη^{\prime}$ is determined to be $(4.84\pm0.03\pm0.24)\times 10^{-3}$, where the first error is statistical and the second systematic.

20 pages, 5 figures, published in PRD