New charm resonances and $J/\psi$ interactions in a hadron gas

TL;DR

This paper investigates how $J/a$ mesons interact with other mesons in the hadron gas phase after heavy ion collisions, finding that these interactions reduce $J/a$ abundance by about 20-24%, with most changes occurring during the QGP phase.

Contribution

It introduces an improved effective Lagrangian approach including $K$, $K^*$, and exotic charmonium states to study $J/a$ interactions in the hadron gas phase.

Findings

$J/a$ interactions reduce its abundance by 20-24% in RHIC and LHC.

Inclusion of $K$, $K^*$, and exotic states enhances the interaction modeling.

Most $J/a$ abundance changes occur during the QGP phase.

Abstract

In relativistic heavy ion collisions, after the quark gluon plasma (QGP) phase there is a hadron gas (HG) phase. In both phases $J/\psi$ may be formed and destroyed. In this note we study the $J/\psi$ interactions with other mesons in the hadron gas phase. Making use of effective field Lagrangians we obtain the cross sections for the production and absorption processes. With respect to the existing calculations, the improvements introduced here are the inclusion of $K$ and $K^*$'s in the effective Lagrangian approach and the inclusion of processes involving the new exotic charmonium states $Z_c(3900)$ and $Z_c(4025)$. We conclude that the interactions between $J/\psi$ and all the considered mesons reduce the original $J/\psi$ abundance ( determined at the end of the quark gluon plasma phase ) by 20 \% and 24 \% in RHIC and LHC collisions respectively. Consequently, any really significant change in the $J/\psi$ abundance comes from dissociation and regeneration processes in the QGP phase.