Observation of associated near-side and away-side long-range correlations in sqrt[s(NN)]=5.02 TeV proton-lead collisions with the ATLAS detector.

Two-particle correlations in relative azimuthal angle (Δø) and pseudorapidity (Δη) are measured in sqrt[s(NN)] = 5.02 TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1 μb(-1) of data as a function of transverse momentum (p(T)) and the trans...

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Bibliographic Details
Main Authors: Aad, G, Abajyan, T, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, A, Abdinov, O, Aben, R, Abi, B, Abolins, M, Abouzeid, O, Abramowicz, H, Abreu, H, Acharya, B, Adamczyk, L, Adams, D, Addy, T, Adelman, J, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, J, Agustoni, M, Ahlen, S
Format: Journal article
Language:English
Published: 2013
Description
Summary:Two-particle correlations in relative azimuthal angle (Δø) and pseudorapidity (Δη) are measured in sqrt[s(NN)] = 5.02 TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1 μb(-1) of data as a function of transverse momentum (p(T)) and the transverse energy (ΣE(T)(Pb)) summed over 3.1 < η < 4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2 < |Δ η | < 5) "near-side" (Δø ~ 0) correlation that grows rapidly with increasing ΣE(T)(Pb). A long-range "away-side" (Δø ~ π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣE(T)(Pb), is found to match the near-side correlation in magnitude, shape (in Δη and Δø) and ΣE(T)(Pb) dependence. The resultant Δø correlation is approximately symmetric about π/2, and is consistent with a dominant cos2Δø modulation for all ΣE(T)(Pb) ranges and particle p(T).