Speaker
Description
Measurements of open heavy-flavor hadron and quarkonium
in heavy-ion collisions provide a powerful tool
to study both initial-state effects on heavy-quark production and final-state interactions
between heavy quarks and the quark-gluon plasma (QGP).
Recent ATLAS measurements of azimuthal anisotropy of muons from heavy-flavor decays in pp and Pb+Pb collisions are presented.
Muons with charm and bottom origins are separated from each other
based on the transverse impact parameter with respect to the primary collision vertex.
Muons from both charm and bottom hadrons are
found to have significant azimuthal anisotropies in Pb+Pb collisions,
with larger anisotropies for muons from charm hadrons than for muons from bottom hadrons observed.
In pp collisions, the azimuthal anisotropy of muons from charm hadron decays
is similar to that of light hadrons,
while muons from bottom hadron decays show no significant anisotropy.
The different patterns in Pb+Pb and pp collisions challenge the picture
of a common origin of azimuthal anisotropy for heavy flavor in different systems.
New ATLAS measurements of suppression of muons from heavy flavor decays
and bottomonia in Pb+Pb collisions are also presented.
The relative suppression between different bottomonium states in Pb+Pb,
together with the same observable measured in p+Pb collisions,
provides strong constraints on the relative contributions of initial- and final-state effects on the observed suppression.
