Search for di-photon decays of an axion-like particle in radiative
$J/\psi$ decays
Search for di-photon decays of an axion-like particle in radiative
$J/\psi$ decays
We search for the di-photon decay of a light pseudoscalar axion-like particle, $a$, in radiative $J/\psi$ decays, using 10 billion $J/\psi$ events collected with the BESIII detector. We find no evidence of a signal and set upper limits at the $95\%$ confidence level on the product branching fraction $\mathcal{B}(J/\psi \to …