Measurement of the suppression and azimuthal anisotropy of muons from heavy-flavor decays in Pb+Pb collisions at √sNN=2.76 TeV with the ATLAS detector
Aaboud, Morad; Aad, Georges; Abbott, Brad; Abdinov, Ovsat Bahram oglu; Abeloos, Baptiste; Abhayasinghe, Deshan Kavishka; Abidi, Syed Haider; AbouZeid, Hass; Abraham, Nadine L.; Abramowicz, Halina; Buanes, Trygve; Eigen, Gerald; Fomin, Nikolai; Lipniacka, Anna; Martin dit Latour, Bertrand; Mæland, Steffen; Stugu, Bjarne; Yang, Zongchang; Zalieckas, Justas; Bugge, Magnar Kopangen; Cameron, David Gordon; Catmore, James Richard; Feigl, Simon; Franconi, Laura; Garonne, Vincent; Gramstad, Eirik; Hellesund, Simen; Morisbak, Vanja; Oppen, Henrik; Ould-Saada, Farid; Pedersen, Maiken; Read, Alexander Lincoln; Røhne, Ole Myren; Sandaker, Heidi; Serfon, Cédric; Stapnes, Steinar; Vadla, Knut Oddvar Høie; Abreu, Henso; Abulaiti, Yiming; Acharya, Bobby S.; Adachi, Shunsuke; Adamczyk, Leszek; Adelman, Jareed; Adersberger, Michael; Adigüzel, Aytül; Adye, Tim; Affolder, Anthony Allen; Afik, Yoav; Agheorghiesei, Catalin; Aguilar Saavedra, Juan Antonio; ATLAS, Collaboration
Peer reviewed, Journal article
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ATLAS measurements of the production of muons from heavy-flavor decays in √sNN=2.76 TeV Pb+Pb collisions and √s=2.76 TeV pp collisions at the LHC are presented. Integrated luminosities of 0.14 nb−1 and 570 nb−1 are used for the Pb+Pb and pp measurements, respectively, which are performed over the muon transverse momentum range 4<pT<14 GeV and for five Pb+Pb centrality intervals. Backgrounds arising from in-flight pion and kaon decays, hadronic showers, and misreconstructed muons are statistically removed using a template-fitting 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 RAA obtained from these is observed to be independent of pT, within uncertainties, and to be less than unity, which indicates suppressed production of heavy-flavor muons in Pb+Pb collisions. For the 10% most central Pb+Pb events, the measured RAA is approximately 0.35. The azimuthal modulation of the heavy-flavor muon yields is also measured and the associated Fourier coefficients vn for n=2, 3, and 4 are given as a function of pT and centrality. They vary slowly with pT and show a systematic variation with centrality which is characteristic of other anisotropy measurements, such as that observed for inclusive hadrons. The measured RAA and vnvalues are also compared with theoretical calculations.