Cold and hot nuclear matter effects on $J/\psi$ production at RHIC-BES energies

TL;DR

This study investigates how cold and hot nuclear matter effects influence $J/$ production in Au-Au collisions at RHIC-BES energies, revealing the decreasing significance of QGP effects at lower energies.

Contribution

It provides a systematic analysis of nuclear effects on $J/$ production across a range of collision energies using a transport approach.

Findings

Nuclear absorption increases as energy decreases.

Shadowing effects transition from anti-shadowing to shadowing with decreasing energy.

QGP effects become negligible at 14.5 GeV.

Abstract

Integrated and differential $J/\psi\ R_{AA}$ are systematically studied in Au-Au collisions at RHIC-BES energies in a transport approach, including cold and hot nuclear effects respectively in the initial condition and the collision terms. With decreasing energy, while the temperature, life time and size of the QGP fireball decrease, the nuclear absorption of the initially produced charmonia is more and more strong, and the nuclear shadowing effect on charmonium regeneration goes to anti-shadowing first and then to shadowing again. As a competition between the cold and hot nuclear effects, the QGP phase is still important for charmonium production at $\sqrt{s_{NN}}$=200, 62.4, 54.4 and 39 GeV but becomes negligible at $\sqrt{s_{NN}}$=14.5 GeV.