Measurement of two-particle correlations with respect to second- and third-order event planes in Au + Au collisions at √sNN=200 GeV

Adare, A.
Hill, John
Hotvedt, Nels
Kempel, Todd
Lajoie, John
Lebedev, Alexandre
Lee, S. H.
Ogilvie, Craig
Patel, Milap
Pei, H.
Rinn, Timothy
Rosati, Marzia
Runchey, Jonathan
Semenov, Alexey
Shimomura, M.
Vale, Carla
Wei, Feng
et al.
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We present measurements of azimuthal correlations of charged hadron pairs in root s(NN) = 200 GeV Au + Au collisions for the trigger and associated particle transverse-momentum ranges of 1 < p(T)(t) < 10 GeV/c and 0.5 < p(T)(a) < 10 GeV/c. After subtraction of an underlying event using a model that includes higher-order azimuthal anisotropy v(2), v(3,) and v(4), the away-side yield of the highest trigger-p(T)(p(T)(t) > 4 GeV/c) correlations is suppressed compared with that of correlations measured in p + p collisions. At the lowest associated particle p(T)(0.5 < p(T)(a) < 1 GeV/c), the away-side shape and yield are modified relative to those in p + p collisions. These observations are consistent with the scenario of radiative-jet energy loss. For the low-p(T) trigger correlations (2 < p(T)(t) < 4 GeV/c), a finite away-side yield exists and we explore the dependence of the shape of the away-side within the context of an underlying-event model. Correlations are also studied differentially versus event-plane angle Psi(2) and Psi(3). The angular correlations show an asymmetry when selecting the sign of the difference between the trigger-particle azimuthal angle and the Psi(2) event plane. This asymmetry and the measured suppression of the pair yield out-of-plane is consistent with a path-length-dependent energy loss. No Psi(3) dependence can be resolved within experimental uncertainties.


This article is published as Adare, A., S. Afanasiev, C. Aidala, N. N. Ajitanand, Y. Akiba, H. Al-Bataineh, J. Alexander et al. "Measurement of two-particle correlations with respect to second-and third-order event planes in Au+ Au collisions at s NN= 200 GeV." Physical Review C 99, no. 5 (2019): 054903. DOI: 10.1103/PhysRevC.99.054903. Posted with permission.