Measurement of long-range pseudorapidity correlations and azimuthal harmonics in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Allbrooke, B M M, Asquith, L, Cerri, A, Chavez Barajas, C A, De Santo, A, Salvatore, F, Santoyo Castillo, I, Suruliz, K, Sutton, M R, Vivarelli, I and The ATLAS Collaboration, et al. (2014) Measurement of long-range pseudorapidity correlations and azimuthal harmonics in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector. Physical Review C, 90 (044906). ISSN 2469-9985

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Abstract

Measurements of two-particle correlation functions and the first five azimuthal harmonics, v1 to v5, are presented, using 28 nb−1 of p+Pb collisions at a nucleon-nucleon center-of-mass energy of √sNN=5.02 TeV measured with the ATLAS detector at the LHC. Significant long-range “ridgelike” correlations are observed for pairs with small relative azimuthal angle (|Δϕ|<π/3) and back-to-back pairs (|Δϕ|>2π/3) over the transverse momentum range 0.4<pT<12 GeV and in different intervals of event activity. The event activity is defined by either the number of reconstructed tracks or the total transverse energy on the Pb-fragmentation side. The azimuthal structure of such long-range correlations is Fourier decomposed to obtain the harmonics vn as a function of pT and event activity. The extracted vn values for n=2 to 5 decrease with n. The v2 and v3 values are found to be positive in the measured pT range. The v1 is also measured as a function of pT and is observed to change sign around pT≈1.5–2.0 GeV and then increase to about 0.1 for pT>4 GeV. The v2(pT), v3(pT), and v4(pT) are compared to the vn coefficients in Pb+Pb collisions at √sNN=2.76 TeV with similar event multiplicities. Reasonable agreement is observed after accounting for the difference in the average pT of particles produced in the two collision systems.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Experimental Particle Physics Research Group
Subjects: Q Science > QC Physics
Depositing User: Billy Wichaidit
Date Deposited: 03 May 2017 08:52
Last Modified: 03 May 2017 09:01
URI: http://sro.sussex.ac.uk/id/eprint/67628

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Project NameSussex Project NumberFunderFunder Ref
ATLASG0275STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCILST/I006048/1