Search for $\eta_c(2S)\to\omega\omega$ and $\omega\phi$ decays and measurements of $\chi_{cJ}\to\omega\omega$ and $\omega\phi$ in $\psi(2S)$ radiative processes

TL;DR

This study searches for specific decay modes of the $ ext{eta}_c(2S)$ particle and measures branching fractions of $ ext{chi}_cJ$ decays, providing new experimental insights into charmonium decay processes.

Contribution

First evidence for $ ext{eta}_c(2S) o ext{omega} ext{omega}$ decay and updated measurements of $ ext{chi}_cJ$ decay branching fractions in $ ext{psi}(2S)$ radiative processes.

Findings

Evidence of $ ext{eta}_c(2S) o ext{omega} ext{omega}$ with 3.2$\sigma$ significance.

Measured branching fraction for $ ext{eta}_c(2S) o ext{omega} ext{omega}$: $(5.65\pm3.77 ext{(stat.)}\pm5.32 ext{(syst.)}) imes10^{-4}$.

Upper limit for $ ext{eta}_c(2S) o ext{omega} ext{phi}$ decay: $<2.24 imes10^{-7}$ at 90\% confidence level.

Abstract

Using $(2712\pm 14)$ $\times$ 10$^{6}$ $\psi(2S)$ events collected with the BESIII detector at the BEPCII collider, we search for the decays $\eta_{c}(2S)\to\omega\omega$ and $\eta_{c}(2S)\to\omega\phi$ via the process $\psi(2S)\to\gamma\eta_{c}(2S)$. Evidence of $\eta_{c}(2S)\to\omega\omega$ is found with a statistical significance of $3.2\sigma$. The branching fraction is measured to be $\mathcal{B}(\eta_{c}(2S)\to\omega\omega)=(5.65\pm3.77(\rm stat.)\pm5.32(\rm syst.))\times10^{-4}$. No statistically significant signal is observed for the decay $\eta_{c}(2S)\to\omega\phi$. The upper limit of the branching fraction at the 90\% confidence level is determined to be $\mathcal{B}(\psi(2S)\to\gamma\eta_{c}(2S),\eta_{c}(2S)\to\omega\phi)<2.24\times 10^{-7}$. We also update the branching fractions of $\chi_{cJ}\to \omega\omega$ and $\chi_{cJ}\to\omega\phi$ decays via the $\psi(2S)\to\gamma\chi_{cJ}$ transition. The branching fractions are determined to be $\mathcal{B}(\chi_{c0}\to\omega\omega)=(10.63\pm0.11\pm0.46)\times 10^{-4}$, $\mathcal{B}(\chi_{c1}\to\omega\omega)=(6.39\pm0.07\pm0.29)\times 10^{-4}$, $\mathcal{B}(\chi_{c2}\to\omega\omega)=(8.50\pm0.08\pm0.38)\times 10^{-4}$, $\mathcal{B}(\chi_{c0}\to\omega\phi)=(1.18\pm0.03\pm0.05)\times 10^{-4}$, $\mathcal{B}(\chi_{c1}\to\omega\phi)=(2.03\pm0.15\pm0.12)\times 10^{-5}$, and $\mathcal{B}(\chi_{c2}\to\omega\phi)=(9.37\pm1.07\pm0.59)\times 10^{-6}$, where the first uncertainties are statistical and the second are systematic.