J/psi suppression at forward rapidity in Au+Au collisions at sqrt(s_NN)=39 and 62.4 GeV

TL;DR

This paper measures J/psi yields in Au+Au collisions at 39 and 62.4 GeV, revealing similar suppression patterns to higher energies, challenging existing theoretical models of quarkonium suppression.

Contribution

It provides new experimental data on J/psi suppression at lower collision energies and compares these with higher energy results to test theoretical models.

Findings

J/psi suppression patterns are similar at 39, 62.4, and 200 GeV.

Suppression presents a challenge to models with energy-dependent mechanisms.

Results suggest complex interplay of suppression and enhancement effects.

Abstract

We present measurements of the J/psi invariant yields in sqrt(s_NN)=39 and 62.4 GeV Au+Au collisions at forward rapidity (1.2<|y|<2.2). Invariant yields are presented as a function of both collision centrality and transverse momentum. Nuclear modifications are obtained for central relative to peripheral Au+Au collisions (R_CP) and for various centrality selections in Au+Au relative to scaled p+p cross sections obtained from other measurements (R_AA). The observed suppression patterns at 39 and 62.4 GeV are quite similar to those previously measured at 200 GeV. This similar suppression presents a challenge to theoretical models that contain various competing mechanisms with different energy dependencies, some of which cause suppression and others enhancement.