Publication
Title
Studies of azimuthal dihadron correlations in ultra-central PbPb collisions at $\sqrt{S_{NN}}$ = 2.76 TeV
Author
Institution/Organisation
CMS Collaboration
Abstract
 Azimuthal dihadron correlations of charged particles have been measured in PbPb collisions at = 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 mu b -aEuro parts per thousand 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 v (2) to v (6), are extracted as a function of particle transverse momentum. At higher transverse momentum, the v (2) harmonic becomes significantly smaller than the higher-order v (n) (n a parts per thousand yenaEuro parts per thousand 3). The p (T)-averaged v (2) and v (3) are found to be equal within 2%, while higher-order v (n) 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.
Language
English
Source (journal)
Journal of high energy physics. - Bristol
Publication
Bristol : 2014
ISSN
1126-6708
1029-8479 [online]
Volume/pages
2(2014), p. 1-38
Article Reference
088
ISI
000331974800001
Medium
E-only publicatie
Full text (Publisher's DOI)
Full text (open access)
UAntwerpen
 Faculty/Department Research group [E?say:metaLocaldata.cgzprojectinf] Publication type Subject Affiliation Publications with a UAntwerp address