Production of hidden-charm molecular candidates in $\psi (4660)$ decays

We investigate the production of several hidden-charm exotic candidates, including $Z_c(3900)$, $Z_c(4020)$, $Z_{cs}(3985)$, and $Z_2(4250)$, in $\psi (4660)$ decays under the assumption that these states are predominantly hadronic molecules. Treating $\psi (4660)$ as a conventional $\psi (5S)$ charmonium state, the production mechanisms are described through intermediate charmed-meson triangle loops, with its couplings to charmed-meson pairs estimated within the quark model. A systematic analysis of the processes $\psi (4660)\to Z_c(3900)\pi$, $\psi (4660)\to Z_c(4020)\pi$, $\psi (4660)\to Z_{cs}(3985)K$, and $\psi (4660)\to Z_2(4250)\pi$ is performed within a unified framework. The predicted branching fractions are found to be of the order of ${10}^{-2}$, ${10}^{-4}$, ${10}^{-3}$, and ${10}^{-6}$, respectively, exhibiting only a mild dependence on the cutoff parameter. We further find that the contributions from the $SHH$ intermediate loops dominate over those from the $THH$ and $HHH$ loops in most channels. The sizable production rates obtained in this work indicate that $\psi (4660)$ decays provide a promising platform for probing the molecular nature of charged hidden-charm exotic states and testing their underlying production mechanisms.