Azimuthal dihadron correlations of charged particles have been measured in PbPb collisions at √sNN = 2.76TeV by the CMS collaboration, using data from the 2011 LHC heavy-ion run. The data set incluDes a sample of ultra-central (0-0.2% centrality) PbPb events collected using a trigger based on total transverse energy in the hadron forward calorimeters and the total multiplicity of pixel clusters in the silicon pixel tracker. A total of about 1.8 million ultra-central events were recorDed, corresponding to an integrated luminosity of 120 μb-1. The observed correlations in ultra-central PbPb events are expected to be particularly sensitive to initial-state fluctuations. The single-particle anisotropy Fourier harmonics, from v2 to v6, are extracted as a function of particle transverse momentum. At higher transverse momentum, the v2 harmonic becomes significantly smaller than the higher-orDer vn (n ≥ 3). The pT-averaged v2 and v3 are found to be equal within 2%, while higher-orDer vn Decrease as n increases. The breakdown of factorization of dihadron correlations into single-particle azimuthal anisotropies is observed. This effect is found to be most prominent in the ultra-central PbPb collisions, where the initial-state fluctuations play a dominant role. A comparison of the factorization data to hydrodynamic predictions with event-by-event fluctuating initial conditions is also presented.

Chatrchyan, S., Khachatryan, V., Sirunyan, A., Tumasyan, A., Adam, W., Bergauer, T., et al. (2014). Studies of azimuthal dihadron correlations in ultra-central PbPb collisions at √sNN = 2.76 TeV. JOURNAL OF HIGH ENERGY PHYSICS, 2014(2) [10.1007/JHEP02(2014)088].

Studies of azimuthal dihadron correlations in ultra-central PbPb collisions at √sNN = 2.76 TeV

BENAGLIA, ANDREA DAVIDE;DINARDO, MAURO EMANUELE;FIORENDI, SARA;GHEZZI, ALESSIO;GOVONI, PIETRO;LUCCHINI, MARCO TOLIMAN;MANZONI, RICCARDO ANDREA;MARTELLI, ARABELLA;MORONI, LUIGI;PAGANONI, MARCO;RAGAZZI, STEFANO;TABARELLI DE FATIS, TOMMASO;Branca, A;De Guio, F;
2014

Abstract

Azimuthal dihadron correlations of charged particles have been measured in PbPb collisions at √sNN = 2.76TeV by the CMS collaboration, using data from the 2011 LHC heavy-ion run. The data set incluDes a sample of ultra-central (0-0.2% centrality) PbPb events collected using a trigger based on total transverse energy in the hadron forward calorimeters and the total multiplicity of pixel clusters in the silicon pixel tracker. A total of about 1.8 million ultra-central events were recorDed, corresponding to an integrated luminosity of 120 μb-1. The observed correlations in ultra-central PbPb events are expected to be particularly sensitive to initial-state fluctuations. The single-particle anisotropy Fourier harmonics, from v2 to v6, are extracted as a function of particle transverse momentum. At higher transverse momentum, the v2 harmonic becomes significantly smaller than the higher-orDer vn (n ≥ 3). The pT-averaged v2 and v3 are found to be equal within 2%, while higher-orDer vn Decrease as n increases. The breakdown of factorization of dihadron correlations into single-particle azimuthal anisotropies is observed. This effect is found to be most prominent in the ultra-central PbPb collisions, where the initial-state fluctuations play a dominant role. A comparison of the factorization data to hydrodynamic predictions with event-by-event fluctuating initial conditions is also presented.
Articolo in rivista - Articolo scientifico
Harmonic flow; Heavy Ions; Relativistic heavy ion physics; Nuclear and High Energy Physics
English
2014
2014
2
088
none
Chatrchyan, S., Khachatryan, V., Sirunyan, A., Tumasyan, A., Adam, W., Bergauer, T., et al. (2014). Studies of azimuthal dihadron correlations in ultra-central PbPb collisions at √sNN = 2.76 TeV. JOURNAL OF HIGH ENERGY PHYSICS, 2014(2) [10.1007/JHEP02(2014)088].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/154131
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