Search for $\psi(3686)\to \gamma\eta_c(\eta(1405))\to \gamma \pi^{+}\pi^{-}\pi^{0}$

TL;DR

This study searches for rare isospin-violating decays of $ ext{eta}_c$ and $ ext{eta}(1405)$ in $ ext{psi}(3686)$ radiative decays, setting upper limits on their branching fractions due to no observed signals.

Contribution

First search for $ ext{eta}_c$ and $ ext{eta}(1405)$ decays into $ ext{pi}^+ ext{pi}^- ext{pi}^0$ in $ ext{psi}(3686)$ radiative decays, establishing upper limits on their branching fractions.

Findings

No signals observed for the decays.

Upper limit on $ ext{BR}( ext{psi}(3686) o ext{gamma} ext{eta}_c o ext{gamma} ext{pi}^+ ext{pi}^- ext{pi}^0)$ is $1.6 imes10^{-6}$.

Upper limit on $ ext{BR}( ext{psi}(3686) o ext{gamma} ext{eta}(1405) o ext{gamma}f_0(980) ext{pi}^0 o ext{gamma} ext{pi}^+ ext{pi}^- ext{pi}^0)$ is $5.0 imes10^{-7}$.

Abstract

Using a sample of $448.1\times10^{6}$ $\psi(3686)$ events collected with the BESIII detector, a search for the isospin violating decay $\eta_{c}\to\pi^{+}\pi^{-}\pi^{0}$ via $\psi(3686)\to\gamma\eta_{c}$ is presented. No signal is observed, and the upper limit on $\mathcal{B}(\psi(3686)\to \gamma\eta_{c}\to \gamma\pi^{+}\pi^{-}\pi^{0} )$ is determined to be $1.6\times10^{-6}$ at the $90\%$ confidence level. In addition, a search for $\eta(1405)\to f_{0}(980)\pi^{0}$ in $\psi(3686)$ radiative decays is performed. No signal is observed, and the branching fraction $\mathcal{B}(\psi(3686)\to\gamma\eta(1405)\to \gamma f_{0}(980)\pi^{0}\to\gamma \pi^+\pi^-\pi^0 )$ is calculated to be less than $ 5.0\times10^{-7}$ at the $90\%$ confidence level.