Evidence for collectivity in pp collisions at the LHC
Author(s)
Abercrombie, Daniel Robert; Allen, Brandon Leigh; Apyan, Aram; Barbieri, Richard Alexander; Baty, Austin Alan; Bi, Ran; Bierwagen, Katharina; Brandt, Stephanie Akemi; Cali, Ivan Amos; Busza, Wit; 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 D.; Luckey Jr, P David; 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.; Wyslouch, Boleslaw; Yang, Mingming; Wyslouch, Victoria; Wang, Ta-Wei; ... Show more Show less
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Measurements of two- and multi-particle angular correlations in pp collisions at √s=5, 7, and 13 TeV are presented as a function of charged-particle multiplicity. The data, corresponding to integrated luminosities of 1.0pb[superscript −1] (5 TeV), 6.2pb[superscript −1] (7 TeV), and 0.7pb[superscript −1] (13 TeV), were collected using the CMS detector at the LHC. The second-order (v[subscript 2]) and third-order (v[subscript 3]) azimuthal anisotropy harmonics of unidentified charged particles, as well as v[subscript 2] of K[superscript 0][subscript s] and Λ/[bar over Λ] particles, are extracted from long-range two-particle correlations as functions of particle multiplicity and transverse momentum. For high-multiplicity pp events, a mass ordering is observed for the v[subscript 2] values of charged hadrons (mostly pions), K[superscript 0][subscript s], and Λ/[bar overΛ], with lighter particle species exhibiting a stronger azimuthal anisotropy signal below p[subscript T] ≈2 GeV/c. For 13 TeV data, the v[subscript 2] signals are also extracted from four- and six-particle correlations for the first time in pp collisions, with comparable magnitude to those from two-particle correlations. These observations are similar to those seen in pPb and PbPb collisions, and support the interpretation of a collective origin for the observed long-range correlations in high-multiplicity pp collisions. Keywords: CMS, Physics, Heavy ion, Ridge, Correlation, pp
Date issued
2017-02Department
Massachusetts Institute of Technology. Department of Physics; Massachusetts Institute of Technology. Laboratory for Nuclear ScienceJournal
Physics Letters B
Publisher
Elsevier BV
Citation
Khachatryan, V., et al. “Evidence for Collectivity in Pp Collisions at the LHC.” Physics Letters B, vol. 765, Feb. 2017, pp. 193–220. © 2016 The Authors
Version: Final published version
ISSN
03702693