Abstract
Measurements of the production of muons from heavy-flavour hadron decays in Pb–Pb collisions at sNN=5.02 and 2.76 TeV using the ALICE detector at the LHC are reported. The nuclear modification factor RAA at sNN=5.02 TeV is measured at forward rapidity (2.5<y<4) as a function of transverse momentum pT in central, semi-central, and peripheral collisions over a wide pT interval, 3<pT<20 GeV/c, in which muons from beauty-hadron decays are expected to take over from charm as the dominant source at high pT (pT>7 GeV/c). The RAA shows an increase of the suppression of the yields of muons from heavy-flavour hadron decays with increasing centrality. A suppression by a factor of about three is observed in the 10% most central collisions. The RAA at sNN=5.02 TeV is similar to that at sNN=2.76 TeV. The precise RAA measurements have the potential to distinguish between model predictions implementing different mechanisms of parton energy loss in the high-density medium formed in heavy-ion collisions. They place important constraints for the understanding of the heavy-quark interaction with the hot and dense QCD medium.
Highlights
The study of ultra-relativistic heavy-ion collisions aims to investigate a state of strongly-interacting matter at high energy density and temperature
The pT-differential yields of muons from heavy-flavour hadron decays normalised to the equivalent number of minimum bias (MB) events at forward rapidity
An increasing reduction of the yield of muons from heavy-flavour hadron decays with increasing centrality with respect to the pp reference scaled by the average nuclear overlap function is clearly seen
Summary
The study of ultra-relativistic heavy-ion collisions aims to investigate a state of strongly-interacting matter at high energy density and temperature Under these extreme conditions, quantum chromodynamics (QCD) calculations on the lattice predict the formation of a quark–gluon plasma (QGP), where quarks and gluons are deconfined, and chiral symmetry is partially restored [1,2,3,4]. Heavy quarks (charm and beauty) are key probes of the QGP properties in the laboratory They are predominantly created in hard-scattering processes at the early stage of the collision on a timescale shorter than the formation time of the QGP of ∼ 0.1–1 fm/c [5,6].
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