Modelling J/psi production and absorption in a microscopic nonequilibrium approach

TL;DR

This paper models J/psi production and absorption in heavy ion collisions using a microscopic nonequilibrium approach, comparing different dissociation scenarios and analyzing various interaction effects to understand suppression patterns.

Contribution

It introduces a detailed microscopic model that distinguishes between color-singlet and color-octet states and examines their impact on J/psi suppression in heavy ion collisions.

Findings

Both hadronic scenarios match measured J/psi production cross sections.

Rapidity dependence of suppression can discriminate between models.

Interactions with secondary hadrons significantly influence J/psi absorption.

Abstract

Charmonium production and absorption in heavy ion collisions is studied with the Ultrarelativisitic Quantum Molecular Dynamics model. We compare the scenario of universal and time independent color-octet dissociation cross sections with one of distinct color-singlet J/psi, psi' and chi_c states, evolving from small, color transparent configurations to their asymptotic sizes. The measured J/psi production cross sections in pA and AB collisions at SPS energies are consistent with both - purely hadronic - scenarios. The predicted rapidity dependence of J/psi suppression can be used to discriminate between the two experimentally. The importance of interactions with secondary hadrons and the applicability of thermal reaction kinetics to J/psi absorption are investigated. We discuss the effect of nuclear stopping and the role of leading hadrons. The dependence of the psi' to J/psi ratio on the model assumptions and the possible influence of refeeding processes is also studied.