Study of electromagnetic decay of $J/ψ$ and $ψ^\prime$ to vector and pseudoscalar

Abstract

The electromagnetic decay contributions to $J/ψ(ψ^\prime)\to VP$, where $V$ and $P$ stand for vector and pseudoscalar meson, respectively, are investigated in a vector meson dominance (VMD) model. We show that $J/ψ(ψ^\prime)\to γ^*\to VP$ can be constrained well with the available experimental information. We find that this process has significant contributions in $ψ^\prime\to VP$ and may play a key role in understanding the deviations from the so-called "12% rule" for the branching ratio fractions between $ψ^\prime\to VP$ and $J/ψ\to VP$. We also address that the "12% rule" becomes very empirical in exclusive hadronic decay channels.