Dileptons, Charm and Charmonium at Finite Temperature and Chemical Potential

TL;DR

This paper explores how dileptons, open charm, and charmonia can be used in heavy-ion collisions to probe hot, dense matter at finite quark chemical potential, discussing theoretical frameworks and current experimental insights.

Contribution

It provides a comprehensive analysis of how electromagnetic and heavy-flavor observables can reveal properties of hot and dense QCD matter at finite chemical potential, integrating theoretical models with experimental data.

Findings

Low-mass dileptons are sensitive to baryonic medium effects.

Open-charm signals may be enhanced by a soft $\sigma$ mode.

Charmonium dissociation can be modeled using finite-temperature potential models.

Abstract

We discuss how dileptons, open charm and charmonia may be utilized in heavy-ion collisions to extract information specific to hot and dense matter at finite quark chemical potential, $\mu_q$. For each observable we briefly discuss underlying theoretical frameworks and the current status in interpreting available heavy-ion data at SPS and RHIC energies. Low-mass dileptons are particularly sensitive to baryonic medium effects in spectral modifications of the $\rho$ meson, and may serve as an accurate measure of the fireball lifetime. In the open-charm sector, observable signals may be generated by a ``critical'' enhancement of scattering rates via $t$-channel exchange of a soft $\sigma$ mode. For charmonia, finite-$T$ potential models could be used to extrapolate color-screening effects to finite $\mu_q$ to facilitate a quantitative evaluation of dissociation rates in the medium.