Abstract
Azimuthal anisotropies of muons from charm and bottom hadron decays are measured in Pb+Pb collisions at sNN=5.02TeV. The data were collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2018 with integrated luminosities of 0.5nb−1 and 1.4nb−1, respectively. The kinematic selection for heavy-flavor muons requires transverse momentum 4<pT<30GeV and pseudorapidity |η|<2.0. The dominant sources of muons in this pT range are semi-leptonic decays of charm and bottom hadrons. These heavy-flavor muons are separated from light-hadron decay muons and punch-through hadrons using the momentum imbalance between the measurements in the tracking detector and in the muon spectrometers. Azimuthal anisotropies, quantified by flow coefficients, are measured via the event-plane method for inclusive heavy-flavor muons as a function of the muon pT and in intervals of Pb+Pb collision centrality. Heavy-flavor muons are separated into contributions from charm and bottom hadron decays using the muon transverse impact parameter with respect to the event primary vertex. Non-zero elliptic (v2) and triangular (v3) flow coefficients are extracted for charm and bottom muons, with the charm muon coefficients larger than those for bottom muons for all Pb+Pb collision centralities. The results indicate substantial modification to the charm and bottom quark angular distributions through interactions in the quark-gluon plasma produced in these Pb+Pb collisions, with smaller modifications for the bottom quarks as expected theoretically due to their larger mass.
Highlights
The paradigm for the time evolution of heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) involves the formation and hydrodynamic expansion of a region of hot and dense quark–gluon plasma (QGP) with a small ratio of the shear viscosity to entropy density
The measurement uses a combined 2015 and 2018 data set corresponding to a total integrated luminosity of up to 1.9 nb−1 recorded by the ATLAS experiment at the LHC
The inclusive heavy-flavour muon v2 and v3 values measured in 4 < pT < 30 GeV are observed to decrease with pT for all centrality intervals
Summary
The paradigm for the time evolution of heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) involves the formation and hydrodynamic expansion of a region of hot and dense quark–gluon plasma (QGP) with a small ratio of the shear viscosity to entropy density. In this paradigm, the QGP is considered to be a nearly perfect fluid [1,2]. The heavy quarks persist throughout the dynamical time evolution of the QGP and act as sensitive probes of the hot and dense medium
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
