Measurements of heavy-flavor quark probes of the QGP with the ATLAS detector

Open heavy-flavor hadron production, azimuthal anisotropy and correlations in heavy-ion collisions serve as powerful tools to study quark-gluon plasma (QGP) properties, heavy-flavor energy loss due to interaction with QGP, and heavy-flavor hadronization. This talk presents recent ATLAS results on the azimuthal anisotropy ($v_2$ and $v_3$) and nuclear modification factor ($𝑅_\mathrm{AA}$), separately for muons from charm and bottom hadrons, as well as di-muon azimuthal correlations and yields in Pb+Pb and $𝑝𝑝$ collisions. Muons from both charm and bottom hadrons are found to have significant non-zero, second- and third-order azimuthal anisotropies in Pb+Pb collisions, with larger anisotropies for muons from charm hadrons than for muons from bottom hadrons. We highlight that a precise measurement of $v_3$ for bottom is presented. Muons from both sources are also observed to be strongly suppressed with respect to the $𝑝𝑝$ baseline, in a way that depends on the mass of the parent hadron at low to moderate muon $p_\mathrm{T}$. These studies can help to determine whether collisional or radiative processes dominate the energy loss of HF quarks as they traverse the QGP produced in heavy-ion collisions. In particular, the simultaneous measurement of multiple observables for both charm and bottom with the same detector and technique is crucial in providing constraints to state-of-the-art theoretical predictions. Finally, azimuthal correlations and yields of heavy-flavor muon pairs in Pb+Pb collisions are compared to the $pp$ reference and are quantified by the nuclear-modification factor $𝑅_\mathrm{AA}$, The modifications of the widths of these correlations are also measured.