Search for the electromagnetic Dalitz decays $\chi_{cJ}\to e^{+}e^{-}\phi$

Abstract

Using a data sample of $(2.712 \pm 0.014)\times10^{9}$ $\psi(3686)$ events collected at $\sqrt{s}=3.686$ GeV by the BESIII detector, we search for the rare electromagnetic Dalitz decays $\chi_{cJ}\to e^+e^-\phi~(J=0,\,1,\,2)$ via the radiative transitions $\psi(3686)\to\gamma \chi_{cJ}$. No statistically significant $\chi_{cJ}\to e^+e^-\phi$ signals are observed. The upper limits on the branching fractions of $\chi_{cJ}\to e^+e^-\phi~(J=0,\,1,\,2)$, excluding the $\phi$ resonance to $e^+e^-$ final states, are set to be $2.4\times10^{-7},~6.7\times10^{-7}$ and $4.1\times10^{-7}$ at 90\% confidence level, respectively. This is the first search for the electromagnetic Dalitz transition of P-wave charmonium $\chi_{cJ}$ states to a light vector meson.