Probing new physics scenarios of muon $g-2$ via $J/\psi$ decay at BESIII

Understand

The disagreement between the standard model prediction and the experimental measurement of muon anomalous magnetic moment can be alleviated by invoking an additional particle which is either a vector boson ($X_1$) or a scalar ($X_0$).

• This new particle, with the mass $m_X \lesssim 2 m_\mu$, can be searched for in the decay $J/\psi \to \mu^- \mu^+ X$, where $X$ is missing.
• Our numerical study shows that the search is quite feasible at the BESIII experiment in the parameter space allowed by muon $g-2$ measurements.