Charged-Particle Nuclear Modification Factors in PbPb and pPb Collisions at √sNN = 5.02 TeV
Author(s)Abercrombie, Daniel Robert; Allen, Brandon Leigh; Apyan, Aram; Azzolini, Virginia; Barbieri, Richard Alexander; Baty, Austin Alan; Bi, Ran; Bierwagen, Katharina; Brandt, Stephanie Akemi; Busza, Wit; Cali, Ivan Amos; Demiragli, Zeynep; Di Matteo, Leonardo; Gomez-Ceballos, Guillelmo; Goncharov, Maxim; Hsu, Dylan George; Iiyama, Yutaro; Innocenti, Gian Michele; Klute, Markus; Kovalskyi, Dmytro; Krajczar, Krisztian F.; Lai, Yue Shi; Lee, Yen-Jie; Levin, Andrew Michael; Luckey Jr, P David; Maier, Benedikt; Marini, Andrea Carlo; McGinn, Christopher Francis; Mironov, Camelia Maria; Narayanan, Siddharth Madhavan; Niu, Xinmei; Paus, Christoph M. E.; Roland, Christof E; Roland, Gunther M; Salfeld-Nebgen, Jakob Maxillian Henry; Stephans, George S. F.; Sumorok, Konstanty C; Tatar, Kaya; Varma, Mukund Madhav; Velicanu, Dragos Alexandru; Veverka, Jan; Wang, J.; Wang, Ta-Wei; Wyslouch, Boleslaw; Yang, Mingming; Wyslouch, Victoria; ... Show more Show less
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The spectra of charged particles produced within the pseudorapidity window |η| < 1 at √sNN=5.02 TeV are measured using 404 μb[superscript −1] of PbPb and 27.4 pb[superscript −1] of pp data collected by the CMS detector at the LHC in 2015. The spectra are presented over the transverse momentum ranges spanning 0.5 < p[subscript T] < 400 GeV in pp and 0.7 < p T < 400 GeV in PbPb collisions. The corresponding nuclear modification factor, R AA , is measured in bins of collision centrality. The R AA in the 5% most central collisions shows a maximal suppression by a factor of 7-8 in the p T region of 6-9 GeV. This dip is followed by an increase, which continues up to the highest p T measured, and approaches unity in the vicinity of p[subscript T] = 200 GeV. The R[subscript AA] is compared to theoretical predictions and earlier experimental results at lower collision energies. The newly measured pp spectrum is combined with the pPb spectrum previously published by the CMS collaboration to construct the pPb nuclear modification factor, R[subscript pA], up to 120 GeV. For p T > 20 GeV, R][subscript pA] exhibits weak momentum dependence and shows a moderate enhancement above unity.
DepartmentMassachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear Science
Journal of High Energy Physics
Khachatryan, V., A. M. Sirunyan, A. Tumasyan, W. Adam, E. Asilar, T. Bergauer, et al. “Charged-Particle Nuclear Modification Factors in PbPb and pPb Collisions at √sNN = 5.02 TeV.” Journal of High Energy Physics 2017, no. 4 (April 2017). © 2017 The Authors
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