Influence of hadronic bound states above $T_c$ on heavy-quark observables in Pb+Pb collisions at at the CERN Large Hadron Collider

TL;DR

This paper explores how the presence of hadronic bound states above the critical temperature influences heavy-quark observables in Pb+Pb collisions at the LHC, revealing high sensitivity of these observables to the medium's degrees of freedom.

Contribution

It introduces the impact of hadronic bound states above $T_c$ on heavy-quark observables, highlighting their significant influence on experimental signatures.

Findings

Hadronic bound states above $T_c$ reduce heavy-quark interactions.

Heavy-quark observables are highly sensitive to the medium's active degrees of freedom.

Presence of hadronic states affects nuclear modification factor, elliptic flow, and correlations.

Abstract

We investigate how the possible existence of hadronic bound states above the deconfinement transition temperature $T_c$ affects heavy-quark observables like the nuclear modification factor, the elliptic flow and azimuthal correlations. Lattice QCD calculations suggest that above $T_c$ the effective degrees of freedom might not be exclusively partonic but that a certain fraction of hadronic degrees of freedom might already form at higher temperatures. This is an interesting questions by itself but also has a strong influence on other probes of the strongly interacting matter produced in ultrarelativistic heavy-ion collisions. A substantial fraction of hadronic bound states above $T_c$ reduces on average the interaction of the heavy quarks with colored constituents of the medium. We find that all studied observables are highly sensitive to the active degrees of freedom in the quark-gluon plasma.