Speaker
Description
Heavy flavor production and collectivity in A+A and $p$+A collisions provide insight into the energy loss mechanism and transport properties of heavy quarks in QGP regions of varying sizes and temperatures. This talk presents a comprehensive overview of the latest ATLAS heavy flavor results in different collision systems. Final results on the production of muons from heavy flavor decays in 2.76 TeV Pb+Pb and $pp$ collisions are presented. These feature a strongly suppressed nuclear modification factor and large azimuthal anisotropies that are compared to a variety of theoretical predictions. Then, to better understand the details of heavy quark-QGP interactions and the nature of small collision systems, these measurements are extended to 8.16 TeV $p$+Pb collisions. No significant modification of the heavy flavor production, as measured with prompt D0 and D* mesons, is observed. However, a significant azimuthal anisotropy of heavy flavor particles in $p$+Pb is observed via two-particle correlations for a broad set of heavy flavor signatures, including heavy flavor decay muons, prompt D mesons and J/Psi particles. These new results are compared to the azimuthal anisotropies for similar particles in Pb+Pb collisions, to that for light-flavor particles in p+Pb collisions, and to state-of-the-art theoretical predictions. Together, the lack of a large suppression in the presence of a strong azimuthal anisotropy may help provide strong constraints to models attempting to describe possible QGP formation and dynamics in small systems.
