# Quark Matter 2017

Feb 5 – 11, 2017
Hyatt Regency Chicago
America/Chicago timezone

## Measurement of the suppression and azimuthal anisotropy of heavy flavor muons in lead-lead collisions at \sqrt{s_{\mathrm{NN}}}=2.76TeV with the ATLAS detector

Feb 8, 2017, 3:00 PM
20m
Regency D

### Regency D

Oral Open Heavy Flavors

### Speaker

Brian Cole (Columbia University (US))

### Description

ATLAS measurements are presented on the production of muons from heavy-flavor decays in $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV Pb+Pb collisions and $\sqrt{s}$ = 2.76 TeV $pp$ collisions at the LHC. The measurements are performed over the transverse momentum range 4 <$p_{\mathrm {T}}$< 14 GeV and over the 0-60% centrality interval. Backgrounds arising from in-flight pion and kaon decays, hadronic showers, and mis-reconstructed muons are removed using a template-fit procedure. The heavy-flavor muon differential cross-sections and per-event yields are measured in $pp$ and Pb+Pb collisions, respectively. The nuclear modification factor $R_{\mathrm{AA}}$ is observed to be independent of $p_{\mathrm{T}}$ within uncertainties and to be less than unity, which indicates suppressed production of heavy flavor muons in Pb+Pb collisions. The heavy-flavor muon yield is also measured as a function of the azimuthal angle difference, $\phi-Psi_{2}$, relative to the second-order event plane angle. Fourier coefficients associated with the $\cos(2(\phi-\Psi_{2}))$ modulation, $v_2$ , are measured as a function of $p_{\mathrm{T}}$ and centrality. They vary slowly with $p_\mathrm{T}$ and show a systematic variation with centrality that is characteristic of other $v_2$ measurements. The higher-order harmonics $v_3$ and $v_4$ are also measured. These measurements provide insight into the energy loss mechanism of heavy quarks as they propagate through the hot, dense medium produced in heavy ion collisions.

Collaboration ATLAS Open Heavy Flavors

### Primary author

Brian Cole (Columbia University (US))