$J/\psi$ suppression in the threshold model at RHIC and LHC energy

TL;DR

This paper analyzes $J/C6$ suppression in heavy-ion collisions at RHIC and LHC energies using the threshold model, finding anomalous suppression above certain densities and predicting suppression patterns at LHC.

Contribution

It applies the threshold model to recent RHIC data, estimates suppression thresholds, and predicts $J/C6$ suppression at LHC energies, including QGP formation time.

Findings

$J/C6$ suppression occurs above a threshold density of 3.57 fm^{-2}.

Predicted $J/C6$ suppression factor of 3-4 in central Pb+Pb collisions at LHC.

Estimated QGP formation time ranges between 0.07-0.09 fm/c.

Abstract

In the QGP based threshold model \cite{Blaizot:2000ev,Blaizot:1996nq}, in addition to the normal nuclear absorption, $J/\psi$'s are subjected to an 'anomalous' suppression such that above a threshold density $n_{J/\psi}$, all the $J/\psi$'s are melted. In the threshold model we have analysed the recent PHENIX data on the centrality dependence of $J/\psi$ suppression in Au+Au collisions at RHIC. Feedback from decay of the state $\chi$ is accounted for. $J/\psi$'s are anomalously suppressed above a threshold density, $n_{J/\psi}=3.57\pm 0.17$ $fm^{-2}$. Threshold density for anomalous suppression of the state $\chi$ is uncertain to a large extent, $n_\chi=0.32 \pm 0.32$ $fm^{-2}$. The fraction $F$ of the state $\chi$ can not be determined unambiguously, depending on the nuclear absorption, it can vary from 20% to 40%. We have also predicted for the suppression in Pb+Pb collisions at LHC energy. In central Pb+Pb collisions, $J/\psi$'s are suppressed by a factor of 3-4. Suppression pattern is rather similar to that in Au+Au collisions, if not slighty less in central collisions. Using the PHENIX data on the participant number dependence of the Bjorken energy density, we have also estimated the QGP formation time. For critical temperature $T_c$=192 MeV, estimated QGP formation time ranges between 0.07-0.09 fm/c.