Search for an axion-like particle in radiative $J/\psi$ decays

TL;DR

This study searches for axion-like particles in radiative $J/9$ decays using a large data sample, setting new upper limits on their production and coupling, but finds no evidence of such particles.

Contribution

First search for ALPs in $J/9$ radiative decays with the most stringent constraints to date in the 0.165-1.468 GeV/c^2 mass range.

Findings

No significant ALP signal observed.

Set upper limits on $B(J/9 ightarrow\gamma a)$ and $g_{a\gamma\gamma}$.

Constraints are the most stringent for certain mass ranges.

Abstract

We search for an axion-like particle (ALP) $a$ through the process $\psi(3686)\rightarrow\pi^+\pi^-J/\psi$, $J/\psi\rightarrow\gamma a$, $a\rightarrow\gamma\gamma$ in a data sample of $(2.71\pm0.01)\times10^9$ $\psi(3686)$ events collected by the BESIII detector. No significant ALP signal is observed over the expected background, and the upper limits on the branching fraction of the decay $J/\psi\rightarrow\gamma a$ and the ALP-photon coupling constant $g_{a\gamma\gamma}$ are set at 95% confidence level in the mass range of $0.165\leq m_a\leq2.84\,\mbox{GeV}/c^2$. The limits on $B(J/\psi\rightarrow\gamma a)$ range from $8.3\times10^{-8}$ to $1.8\times10^{-6}$ over the search region, and the constraints on the ALP-photon coupling are the most stringent to date for $0.165\leq m_a\leq1.468\,\mbox{GeV}/c^2$.