J/psi suppression at forward rapidity in Au+Au collisions at sqrt(s_NN)=200 GeV

TL;DR

This study measures J/psi suppression at forward rapidity in Au+Au collisions at 200 GeV, confirming stronger suppression than at midrapidity and comparing results with various theoretical models to understand the underlying physics.

Contribution

It provides new detailed measurements of J/psi yields at forward rapidity, extending previous data to finer centrality and higher transverse momentum bins, and compares these with advanced theoretical models.

Findings

J/psi suppression is stronger at forward rapidity than midrapidity.

Data show suppression beyond cold nuclear matter effects.

Current models cannot fully quantify hot-nuclear-matter suppression.

Abstract

Heavy quarkonia are observed to be suppressed in relativistic heavy ion collisions relative to their production in p+p collisions scaled by the number of binary collisions. In order to determine if this suppression is related to color screening of these states in the produced medium, one needs to account for other nuclear modifications including those in cold nuclear matter. In this paper, we present new measurements from the PHENIX 2007 data set of J/psi yields at forward rapidity (1.2<|y|<2.2) in Au+Au collisions at sqrt(s_NN)=200 GeV. The data confirm the earlier finding that the suppression of J/psi at forward rapidity is stronger than at midrapidity, while also extending the measurement to finer bins in collision centrality and higher transverse momentum (pT). We compare the experimental data to the most recent theoretical calculations that incorporate a variety of physics mechanisms including gluon saturation, gluon shadowing, initial-state parton energy loss, cold nuclear matter breakup, color screening, and charm recombination. We find J/psi suppression beyond cold-nuclear-matter effects. However, the current level of disagreement between models and d+Au data precludes using these models to quantify the hot-nuclear-matter suppression.