Further insights into the "$\rho \pi$ puzzle"

Based on a systematic investigation of $J\mathrm{/}\psi ({\psi }^{\mathrm{\prime }})\to VP$, where $V$ and $P$ stand for light vector and pseudoscalar mesons, we identify the role played by the electromagnetic (EM) transitions and intermediate meson loop transitions, which are essential ingredients for understanding the $J\mathrm{/}\psi$ and ${\psi }^{\mathrm{\prime }}$ couplings to $VP$. We show that on the one hand, the EM transitions have relatively larger interferences in ${\psi }^{\mathrm{\prime }}\to \rho \pi$ and $K^{\ast }\bar{K}+c\mathrm{.}c\mathrm{.}$ as explicitly shown by vector meson dominance (VMD). On the other hand, the strong decay of ${\psi }^{\mathrm{\prime }}$ receives relatively larger destructive interferences from the intermediate meson loop transitions. By identifying these mechanisms in an overall study of $J/\psi(\psi^\prime)\to VP$,weprovideacoherentunderstandingoftheso-called\mathrm{"}$\rho\pi$ puzzle".