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

We search for an axion-like particle (ALP) $a$ through the process $\psi (3686)\to {\pi }^{+}{\pi }^{-}J\mathrm{/}\psi$, $J\mathrm{/}\psi \to \gamma a$, $a\to \gamma \gamma$ in a data sample of $(2.71\pm 0.01)\times {10}^9$ $\psi (3686)$ 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 $J\mathrm{/}\psi \to \gamma a$ and the ALP-photon coupling constant $g_{a\gamma \gamma }$ are set at 95% confidence level in the mass range of $0.165\le m_a\le 2.84GeV\mathrm{/}{c}^2$. The limits on $B(J\mathrm{/}\psi \to \gamma a)$ range from $8.3\times {10}^{-8}$ to $1.8\times {10}^{-6}$ over the search region, and the constraints on the ALP-photon coupling are the most stringent to date for $0.165\le m_a\le 1.468GeV\mathrm{/}{c}^2$.