Measurement with the ATLAS detector of multi-particle azimuthal correlations in p + Pb collisions at s NN = 5.02 TeV
In order to study further the long-range correlations ("ridge") observed recently in p + Pb collisions at = 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 $$μ$$b-1, the parameter $$v_2$$ 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.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Contributing Organization:
- ATLAS Collaboration
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1213861
- Alternate ID(s):
- OSTI ID: 1523871
- Journal Information:
- Physics Letters B, Vol. 725, Issue 1-3; ISSN 0370-2693
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- Netherlands
- Language:
- English
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