Internal Charmonium Evolution in the Quark-Gluon Plasma

TL;DR

This paper models the evolution of charmonium states in quark-gluon plasma using a time-dependent Schrödinger equation, revealing how medium effects influence state formation and nuclear modification factors in heavy-ion collisions.

Contribution

It introduces a dynamic quantum mechanical approach to study charmonium evolution in QGP, highlighting the impact of medium effects on state formation and observable ratios.

Findings

Medium effects significantly alter the evolution timescales of charmonium states.

Color-screening enhances excited state overlap at high temperatures.

The double ratio of nuclear modification factors is sensitive to potential strength and temperature.

Abstract

We employ a time-dependent Schr\"odinger equation to study the evolution of a $c\bar c$ dipole in a quark-gluon plasma (QGP). Medium effects on the heavy-quark potential in the QGP are found to significantly affect the timescales of the internal evolution of the dipole. Color-screening can enhance the overlap of the expanding wavepackage with excited states at high temperature, while it is reduced at lower temperatures where the dipole favors the formation of the charmonium ground state. We investigate the consequences of this mechanism on the double ratio of charmonium nuclear modification factors, $R_{AA}^{\psi(2S)}/R_{AA}^{J/\psi}$, in heavy-ion collisions. The impact of the transition mechanisms on this ratio turns out to be rather sensitive to the attractive strength of the potential, and to its temperature dependence.