Hadronic effects on charmonium elliptic flows in heavy-ion collisions

TL;DR

This paper investigates how hadronic medium effects influence the elliptic flow of charmonium in heavy-ion collisions, highlighting the significance at high transverse momentum and the negligible impact on heavier quarkonia like bottomonia.

Contribution

It introduces a detailed study of hadronic medium effects on charmonium elliptic flows using transport and Langevin equations, emphasizing the role of diffusion coefficients at high transverse momentum.

Findings

Charmonium elliptic flow is significantly enhanced at high pT due to hadronic effects.

Hadronic medium effects are negligible for heavier quarkonia such as bottomonia.

High transverse momentum charmonia are sensitive to hadronic medium interactions.

Abstract

Transport and Langevin equations are employed to study hadronic medium effects on charmonium elliptic flows in heavy-ion collisions. In Pb-Pb collisions, the anisotropic energy density of the quark-gluon plasma (QGP) in the transverse plane is transformed into hadron momentum anisotropy after the phase transition. Charmonia with high transverse momentum $p_T$ are produced via the primordial hard process and undergo different degrees of dissociation along different paths in the QGP. They then scatter with light hadrons in the hadron phase. Both contributions to the charmonium elliptic flows are studied at moderate and high transverse momenta. The elliptic flows of the prompt $J/\psi$ are found to be considerably enhanced at high transverse momentum when the charmonium diffusion coefficients in the hadronic medium are parametrized through the geometry scale approximation. This hadronic medium effect is negligible for quarkonia with larger mass such as bottomonia.