Measurement with the ATLAS detector of multi-particle azimuthal correlations in p +Pb collisions at √{sNN} = 5.02 TeV
Abstract
In order to study further the long-range correlations ("ridge") observed recently in p +Pb collisions at √{sNN} = 5.02 TeV, the second-order azimuthal anisotropy parameter of charged particles, v2, 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 μb-1, the parameter v2 has been obtained using two- and four-particle cumulants over the pseudorapidity range | η | < 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 < η < 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 v2 and its similarity to hydrodynamic predictions provide additional evidence for the importance of final-state effects in p +Pb reactions.
- Publication:
-
Physics Letters B
- Pub Date:
- August 2013
- DOI:
- 10.1016/j.physletb.2013.06.057
- arXiv:
- arXiv:1303.2084
- Bibcode:
- 2013PhLB..725...60A
- Keywords:
-
- High Energy Physics - Experiment;
- Nuclear Experiment
- E-Print:
- 8 pages plus author list (23 pages total), 4 figures, 1 table, submitted to Physics Letters B, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2013-01/ Revised version corresponds to submitted version