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Title: Evidence for collectivity in pp collisions at the LHC

Measurements of two- and multi-particle angular correlations in pp collisions at √s = 5,7, and 13TeV are presented as a function of charged-particle multiplicity. The data, corresponding to integrated luminosities of 1.0pb –1 (5 TeV), 6.2pb –1 (7TeV), and 0.7pb –1 (13 TeV), were collected using the CMS detector at the LHC. The second-order (v 2) and third-order (v 3) azimuthal anisotropy harmonics of unidentified charged particles, as well as v 2 of K S 0 and Λ/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 2 values of charged hadrons (mostly pions), K S 0, and Λ/Λ¯, with lighter particle species exhibiting a stronger azimuthal anisotropy signal below p T ≈ 2GeV/c. For 13 TeV data, the v 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. Finally, 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.
Authors:
 [1]
  1. Yerevan Physics Institute, Yerevan (Armenia). et al.
Publication Date:
Report Number(s):
FERMILAB-PUB-16-255-CMS; CMS-HIN-16-010; CERN-EP-2016-147; arXiv:1606.06198
Journal ID: ISSN 0370-2693; 1471287
Grant/Contract Number:
AC02-07CH11359
Type:
Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 765; Journal ID: ISSN 0370-2693
Publisher:
Elsevier
Research Org:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
CMS Collaboration
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CMS; Physics; Heavy ion; Ridge; Correlation; pp
OSTI Identifier:
1335706
Alternate Identifier(s):
OSTI ID: 1294440

Khachatryan, Vardan. Evidence for collectivity in pp collisions at the LHC. United States: N. p., Web. doi:10.1016/j.physletb.2016.12.009.
Khachatryan, Vardan. Evidence for collectivity in pp collisions at the LHC. United States. doi:10.1016/j.physletb.2016.12.009.
Khachatryan, Vardan. 2016. "Evidence for collectivity in pp collisions at the LHC". United States. doi:10.1016/j.physletb.2016.12.009.
@article{osti_1335706,
title = {Evidence for collectivity in pp collisions at the LHC},
author = {Khachatryan, Vardan},
abstractNote = {Measurements of two- and multi-particle angular correlations in pp collisions at √s = 5,7, and 13TeV are presented as a function of charged-particle multiplicity. The data, corresponding to integrated luminosities of 1.0pb–1 (5 TeV), 6.2pb–1 (7TeV), and 0.7pb–1 (13 TeV), were collected using the CMS detector at the LHC. The second-order (v2) and third-order (v3) azimuthal anisotropy harmonics of unidentified charged particles, as well as v2 of KS0 and Λ/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 v2 values of charged hadrons (mostly pions), KS0, and Λ/Λ¯, with lighter particle species exhibiting a stronger azimuthal anisotropy signal below pT ≈ 2GeV/c. For 13 TeV data, the v2 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. Finally, 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.},
doi = {10.1016/j.physletb.2016.12.009},
journal = {Physics Letters. Section B},
number = ,
volume = 765,
place = {United States},
year = {2016},
month = {12}
}