Measurement of the suppression and azimuthal anisotropy of muons from heavy-flavor decays in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV with the ATLAS detector

• Main Authors: Aperio Bella, Ludovica, Araujo Ferraz, Victor, Arduh, Francisco Anuar, Arratia, Miguel, Bannoura, Arwa, Batista, Santiago Juan, Beck, Hans Peter, Beresford, Lydia, Biglietti, Michela, Brendlinger, Kurt, Bryant, Patrick, Butler, John, Buzatu, Adrian, Calvetti, Milene, Carra, Sonia, Casolino, Mirkoantonio, Cerda Alberich, Leonor, Cheng, Huajie, Chiodini, Gabriele, Cindro, Vladimir, Cortes-Gonzalez, Arely, Dandoy, Jeffrey Rogers, De, Kaushik, Duschinger, Dirk, Escobar, Carlos, Fleischmann, Philipp, Gao, Yongsheng, Gaudiello, Andrea, Gentile, Simonetta, Ghasemi, Sara, Govender, Nicolin, Gross, Eilam, Han, Kunlin, Hara, Kazuhiko, Haywood, Stephen, Heim, Timon Frank-Thomas, Honle, Andreas, Horn, Philipp, Iliadis, Dimitrios, Jacka, Petr, Janus, Piotr Andrzej, Kaczmarska, Anna, Kaluza, Adam, Kareem, Mohammad Jawad, Kiehn, Moritz, Kondo, Takahiko, La Rosa Navarro, Jose Luis, Leite, Marco Aurelio Lisboa, Li, Qi, Lie, Ki, Livan, Michele, Longo, Luigi, Looper, Kristina Anne, Love, Jeremy, Maier, Thomas, Mamuzic, Judita, Mermod, Philippe, Montalbano, Alyssa, Monticelli, Fernando, Moss, Harry James, Muanza, Steve, Nomachi, Masaharu, Nozaki, Mitsuaki, Owen, Rhys Edward, Palka, Marek, Pandini, Carlo Enrico, Paramonov, Alexander, Pereira Peixoto, Ana Paula, Piacquadio, Giacinto, Prince, Sebastien, Rettie, Sebastien, Riu, Imma, Rogan, Christopher Sean, Romaniouk, Anatoli, Rosten, Jonatan Hans, Sahu, Arunika, Scanlon, Timothy Paul, Schwarz, Thomas Andrew, Scornajenghi, Matteo, Scutti, Federico, Serin, Laurent, Shapiro, Marjorie, Sharma, Abhishek, Stamen, Rainer, Tannenwald, Benjamin Bordy, Taylor, Geoffrey, Ungaro, Francesca, Vinogradov, Vladimir, Vlachos, Sotirios, Wang, Jike, Wang, Weitao, Wilk, Fabian, Yang, Hongtao, Bin Yusuff, Imran, Zeitnitz, Christian, Zhao, Pingchuan, Zhou, Maosen, Ziolkowski, Michael, Zur Nedden, Martin, Zwalinski, Lukasz
• Format: Report
• Language: English
• Subjects: angular dependence; angular distribution: anisotropy; background; CERN LHC Coll; differential cross section; hadron; heavy quark: decay; heavy quark: production; K: decay; muon: production; muon: transverse momentum; muon: yield; nucleus; p p: scattering; showers: hadronic; suppression
• ISSN: 2469-9985; 1538-4497; 2469-9993; 0556-2813; 1089-490X
• DOI: 10.3204/pubdb-2019-00095

ATLAS measurements of 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 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 $4 < p_T < 14$ 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 $R_{AA}$ obtained from these is observed to be independent of $p_T$, 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 $R_{AA}$ is approximately 0.35. The azimuthal modulation of the heavy-flavor muon yields is also measured and the associated Fourier coefficients $v_n$ for n=2, 3, and 4 are given as a function of $p_T$ and centrality. They vary slowly with $p_T$ and show a systematic variation with centrality which is characteristic of other anisotropy measurements, such as that observed for inclusive hadrons. The measured $R_{AA}$ and vn values are also compared with theoretical calculations.