Search for diphoton decays of an axionlike particle in radiative J/ψ decays

Abstract

We search for the diphoton decay of a light pseudoscalar axionlike particle, a, in radiative J/ψ decays, using 1010 J/ψ 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 B(J/ψ→γa)×B(a→γγ) and the axionlike particle photon coupling constant gaγγ in the ranges of (3.7–48.5)×10−8 and (2.2–101.8)×10−4 GeV−1, respectively, for 0.18≤ma≤2.85 GeV/c2. These are the most stringent limits to date in this mass region. Published by the American Physical Society 2024