Angular correlations between unidentified charged trigger (t) and associated (a) particles are measured by the ALICE experiment in Pb–Pb collisions at √sNN = 2.76 TeV for transverse momenta 0.25 < pt,aT < 15 GeV/c, where ptT > paT . The shapes of the pair correlation distributions are studied in a variety of collision centrality classes between 0 and 50% of the total hadronic cross section for particles in the pseudorapidity interval |η| < 1.0. Distributions in relative azimuth φ ≡ φt − φa are analyzed for |η| ≡ |ηt − ηa| > 0.8, and are referred to as “long-range correlations”. Fourier components Vn ≡ cos(nφ) are extracted from the long-range azimuthal correlation functions. If particle pairs are correlated to one another through their individual correlation to a common symmetry plane, then the pair anisotropy Vn(ptT , paT ) is fully described in terms of single-particle anisotropies vn(pT ) as Vn(ptT , paT ) = vn(ptT )vn(paT ). This expectation is tested for 1 n 5 by applying a global fit of all Vn(ptT , paT ) to obtain the best values vn{GF}(pT ). It is found that for 2n5, the fit agrees well with data up to paT∼ 3–4 GeV/c, with a trend of increasing deviation as ptT and paT are increased or as collisions become more peripheral. This suggests that no pair correlation harmonic can be described over the full 0.25 < pT < 15 GeV/c range using a single vn(pT ) curve; such a description is however approximately possible for 2 n 5 when paT <4 GeV/c. For the n = 1 harmonic, however, a single v1(pT ) curve is not obtained even within the reduced range paT <4 GeV/c.

Harmonic decomposition of two particle angular correlations in Pb–Pb collisions at √s_NN=2.76 TeV / Aamodt, K., Abelev, B., Abrahantes Quintana, A., Adamová, D., Adare, A.M., Aggarwal, M.M., Aglieri Rinella, G., Agocs, A.G., Agostinelli, A., Aguilar Salazar, S., Ahammed, Z., Ahmad, N., Ahmad Masoodi, A., Ahn, S.U., Akindinov, A., Aleksandrov, D., Alessandro, B., Alfaro Molina, R., Alici, A., Alkin, A., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 708:3-5(2012), pp. 249-264. [10.1016/j.physletb.2012.01.060]

Harmonic decomposition of two particle angular correlations in Pb–Pb collisions at √s_NN=2.76 TeV

Bruno, G. E.;
2012

Abstract

Angular correlations between unidentified charged trigger (t) and associated (a) particles are measured by the ALICE experiment in Pb–Pb collisions at √sNN = 2.76 TeV for transverse momenta 0.25 < pt,aT < 15 GeV/c, where ptT > paT . The shapes of the pair correlation distributions are studied in a variety of collision centrality classes between 0 and 50% of the total hadronic cross section for particles in the pseudorapidity interval |η| < 1.0. Distributions in relative azimuth φ ≡ φt − φa are analyzed for |η| ≡ |ηt − ηa| > 0.8, and are referred to as “long-range correlations”. Fourier components Vn ≡ cos(nφ) are extracted from the long-range azimuthal correlation functions. If particle pairs are correlated to one another through their individual correlation to a common symmetry plane, then the pair anisotropy Vn(ptT , paT ) is fully described in terms of single-particle anisotropies vn(pT ) as Vn(ptT , paT ) = vn(ptT )vn(paT ). This expectation is tested for 1 n 5 by applying a global fit of all Vn(ptT , paT ) to obtain the best values vn{GF}(pT ). It is found that for 2n5, the fit agrees well with data up to paT∼ 3–4 GeV/c, with a trend of increasing deviation as ptT and paT are increased or as collisions become more peripheral. This suggests that no pair correlation harmonic can be described over the full 0.25 < pT < 15 GeV/c range using a single vn(pT ) curve; such a description is however approximately possible for 2 n 5 when paT <4 GeV/c. For the n = 1 harmonic, however, a single v1(pT ) curve is not obtained even within the reduced range paT <4 GeV/c.
2012
http://www.sciencedirect.com/science/article/pii/S0370269312001013
Harmonic decomposition of two particle angular correlations in Pb–Pb collisions at √s_NN=2.76 TeV / Aamodt, K., Abelev, B., Abrahantes Quintana, A., Adamová, D., Adare, A.M., Aggarwal, M.M., Aglieri Rinella, G., Agocs, A.G., Agostinelli, A., Aguilar Salazar, S., Ahammed, Z., Ahmad, N., Ahmad Masoodi, A., Ahn, S.U., Akindinov, A., Aleksandrov, D., Alessandro, B., Alfaro Molina, R., Alici, A., Alkin, A., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - 708:3-5(2012), pp. 249-264. [10.1016/j.physletb.2012.01.060]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11589/3903
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