The R_AA and v_2 of muons from heavy-quark decays in Pb+Pb collisions at sqrt(s_NN)=2.76 TeV with the ATLAS detector

TL;DR

This paper reports measurements of muons from heavy-quark decays in Pb+Pb collisions at 2.76 TeV, revealing suppressed production and elliptic flow patterns indicative of quark-gluon plasma effects.

Contribution

It provides the first detailed measurement of heavy-flavour muon R_AA and v_2 at the LHC energy of 2.76 TeV, highlighting suppression and azimuthal anisotropy.

Findings

Nuclear modification factor R_AA ≈ 0.4 in central collisions

Heavy-flavour muons exhibit elliptic flow (v_2) with centrality dependence

Suppressed heavy-flavour muon yields in Pb+Pb compared to pp collisions

Abstract

The ATLAS experiment measures the production of muons coming from the decays of heavy flavour particles in the kinematic interval 4<p_T<14 GeV and |eta|<1. The measurement is performed in sqrt(s) = 2.76 TeV pp collisions and over the centrality range of 0-60% in sqrt(s_NN) = 2.76 TeV Pb+Pb collisions. The heavy flavour muon differential cross-sections and per-event yields are measured in pp and Pb+Pb collisions, respectively. The nuclear modification factor measured in 0-10% most central collisions is observed to be approximately equal to 0.4 and independent of p_T within uncertainties, which indicates suppressed production of heavy flavour muons in Pb+Pb collisions. The muon yields are also measured as a function of the azimuthal angle with respect to the event plane. Fourier coefficients associated with the second harmonic modulation vary slowly with p_T and show a systematic variation with centrality that is characteristic of other elliptic anisotropy measurements.