"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."

Aad, G., Abajyan, T., Abbott, B., Abdallah, J., Khalek, S.a., Abdelalim, A.a., et al. (2013). Measurement with the ATLAS detector of multi-particle azimuthal correlations in p plus Pb collisions at root s(NN)=5.02 TeV. PHYSICS LETTERS. SECTION B, 725(1-3), 60-78 [10.1016/j.physletb.2013.06.057].

Measurement with the ATLAS detector of multi-particle azimuthal correlations in p plus Pb collisions at root s(NN)=5.02 TeV

CERADINI, Filippo;DI MICCO, Biagio;Di Nardo R;Orestano D;PETRUCCI, FABRIZIO;SALAMANNA, GIUSEPPE;