Measurement of long-range pseudorapidity correlations and azimuthal harmonics in √s<inf>NN</inf> =5.02 TeV proton-lead collisions with the ATLAS detector
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© 2014 CERN, for the ATLAS Collaboration.Measurements of two-particle correlation functions and the first five azimuthal harmonics, v<sup>1</sup> to v<sup>5</sup>, are presented, using 28 nb<sup>-1</sup> 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 (|Δϕ|<π/3) and back-to-back pairs (|Δφ|>2π/3) over the transverse momentum range 0.4<p<inf>T</inf><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 ν<inf>n</inf> as a function of pT and event activity. The extracted ν<inf>n</inf> values for n=2 to 5 decrease with n. The ν<inf>2</inf> and ν<inf>3</inf> values are found to be positive in the measured pT range. The ν<inf>1</inf> 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 ν<inf>2</inf> (pT), ν<inf>3</inf> (pT), and ν<inf>4</inf> (pT) are compared to the ν<inf>n</inf> 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.
AuthorsAad, G; Abbott, B; Abdallah, J; Abdel Khalek, S; Abdinov, O; Aben, R; Abi, B; Abolins, M; Abouzeid, OS; Abramowicz, H; Abreu, H; Abreu, R; Abulaiti, Y; Acharya, BS; Adamczyk, L; Adams, DL; Adelman, J; Adomeit, S; Adye, T; Agatonovic-Jovin, T; Aguilar-Saavedra, JA; Agustoni, M; Ahlen, SP; Ahmadov, F; Aielli, G; Akerstedt, H; Åkesson, TPA; Akimoto, G; Akimov, AV; Alberghi, GL; Albert, J; Albrand, S; Alconada Verzini, MJ; Aleksa, M; Aleksandrov, IN; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Alimonti, G; Alio, L; Alison, J; Allbrooke, BMM; Allison, LJ; Allport, PP; Almond, J; Aloisio, A; Alonso, A; Alonso, F; Alpigiani, C; Altheimer, A; Alvarez Gonzalez, B; Alviggi, MG; Amako, K; Amaral Coutinho, Y; Amelung, C; Amidei, D; Amor Dos Santos, SP; Amorim, A; Amoroso, S; Amram, N; Amundsen, G; Anastopoulos, C; Ancu, LS; Andari, N; Andeen, T; Anders, CF; Anders, G; Anderson, KJ; Andreazza, A; Andrei, V; Anduaga, XS; Angelidakis, S; Angelozzi, I; Anger, P; Angerami, A; Anghinolfi, F; Anisenkov, AV; Anjos, N; Annovi, A; Antonaki, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F
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