Charmonium dynamics in heavy ion collisions

TL;DR

This paper investigates charmonium suppression in heavy ion collisions at RHIC, showing that hadronic interactions alone cannot explain the observed suppression patterns, implying significant pre-hadronic medium effects.

Contribution

It demonstrates that conventional hadronic and color screening models are insufficient, highlighting the importance of strong pre-hadronic interactions in charmonium dynamics.

Findings

Hadronic interactions contribute to suppression but are insufficient alone.

Color screening and hadronic models fail to explain rapidity dependence.

Strong pre-hadronic interactions are necessary to account for observations.

Abstract

Applying the HSD transport approach to charmonium dynamics within the 'hadronic comover model' and the 'QGP melting scenario', we show that the suppression pattern seen at RHIC cannot be explained by the interaction with baryons, comoving mesons and/or by color screening mechanism. The interaction with hadrons in the late stages of the collision (when the energy density falls below the critical) gives a sizable contribution to the suppression. On the other hand, it does not account for the observed additional charmonium dissociation and its dependence on rapidity. Together with the failure of the hadron-string models to reproduce high v2 of open charm mesons, this suggests strong pre-hadronic interaction of c-cbar with the medium at high energy densities.