Measurement with the ATLAS detector of multi-particle azimuthal correlations in <i>p</i> plus Pb collisions at √<i>s</i><sub>NN</sub>=5.02 TeV


Aad G., Abajyan T., Abbott B., Abdallah J., Abdel Khalek S., Abdelalim A., ...More

PHYSICS LETTERS B, no.1-3, pp.60-78, 2013 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2013
  • Doi Number: 10.1016/j.physletb.2013.06.057
  • Journal Name: PHYSICS LETTERS B
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.60-78
  • Ankara University Affiliated: Yes

Abstract

In order to study further the long-range correlations ("ridge") observed recently in p + Pb collisions at root s(NN) = 5.02 TeV, the second-order azimuthal anisotropy parameter of charged particles, v(2), has been measured with the cumulant method using the ATLAS detector at the LHC. In a data sample corresponding to an integrated luminosity of approximately 1 mu b(-1), the parameter v(2) has been obtained using two- and four-particle cumulants over the pseudorapidity range vertical bar eta vertical bar < 2.5. The results are presented as a function of transverse momentum and the event activity, defined in terms of the transverse energy summed over 3.1 < eta < 4.9 in the direction of the Pb beam. They show features characteristic of collective anisotropic flow, similar to that observed in Pb + Pb collisions. A comparison is made to results obtained using two-particle correlation methods, and to predictions from hydrodynamic models of p + Pb collisions. Despite the small transverse spatial extent of the p + Pb collision system, the large magnitude of v(2) and its similarity to hydrodynamic predictions provide additional evidence for the importance of final-state effects in p + Pb reactions. (C) 2013 CERN. Published by Elsevier B.V. All rights reserved.