Heavy flavor relaxation in a hadronic medium

TL;DR

This paper calculates charm and bottom quark transport properties in a hadronic medium relevant to heavy ion collisions, using an effective field theory approach with unitarization to include resonances, and discusses implications for experimental observables.

Contribution

It introduces a novel calculation of heavy flavor transport coefficients in a hadronic medium incorporating unitarized amplitudes and resonance effects, extending previous models.

Findings

Resonance effects enhance heavy flavor diffusion.

Transport coefficients depend on temperature and momentum.

Estimated relaxation lengths inform heavy meson observables.

Abstract

Charm and bottom transport coefficients in a medium constituted of light mesons, such as is formed in the hadronic phase of Heavy Ion Collisions, are obtained within an effective field theory approach implementing heavy quark symmetry and chiral symmetry breaking. Heavy flavor propagates in the medium as $D/B$ and $D^*/B^*$ degrees of freedom, and unitarization of the lowest order heavy-light meson amplitudes is used in order to reach high temperatures. The latter accounts for dynamically generated resonances in isospin 1/2 channels, a feature that leads to a more efficient heavy flavor diffussion. We discuss the temperature and momentum dependence of the friction and diffusion coefficients in a transport approach up to temperatures of about $T\simeq 150$ MeV, and provide estimates of the charm/bottom relaxation lengths and momentum loss. Implications for heavy meson spectrum observables in Heavy Ion Collisions are discussed.