Observation of $J/\psi\to \gamma\eta\pi^{0}$

TL;DR

This paper reports the first measurement of the branching fraction for the decay $J/\rightarrow \gamma\eta\pi^{0}$ and sets upper limits for related intermediate resonances using a large dataset from the BESIII detector.

Contribution

First measurement of the branching fraction for $J/\psi \rightarrow \gamma \eta \pi^{0}$ and first limits on intermediate resonance contributions.

Findings

Branching fraction $\mathcal{B}(J/\psi \rightarrow \gamma \eta \pi^{0})$ measured as $(2.14\pm0.18\pm0.25)\times10^{-5}$.

Upper limits for $J/\psi \rightarrow \gamma a_{0}(980)$ and $a_{2}(1320)$ decays set at 95",

,

Abstract

We present the first study of the process $J/\psi \rightarrow \gamma\eta\pi^{0}$ using $(223.7\pm1.4)\times10^{6}$ $J/\psi$ events accumulated with the BESIII detector at the BEPCII facility. The branching fraction for $J/\psi \rightarrow \gamma\eta\pi^{0}$ is measured to be $\mathcal{B}(J/\psi \rightarrow \gamma\eta\pi^{0}) =(2.14\pm0.18(stat)\pm0.25(syst))\times10^{-5}$. With a Bayesian approach, the upper limits of the branching fractions $\mathcal{B}(J/\psi \rightarrow \gamma a_{0}(980),a_0(980)\rightarrow\eta\pi^0)$ and $\mathcal{B}(J/\psi \rightarrow \gamma a_{2}(1320),a_2(1320)\rightarrow\eta\pi^0)$ are determined to be $2.5\times10^{-6}$ and $6.6\times10^{-6}$ at the 95\% confidence level, respectively. All of these measurements are given for the first time.