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

Abstract: Azimuthal dihadron correlations of charged particles have been measured in PbPb collisions at vsNN =?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.

Otras publicaciones de la misma revista o congreso con autores/as de la Universidad de Cantabria

 Fuente: Journal of High Energy Physics, Vol. 2014, Num. 2, Art. Num. 88

Editorial: Springer Verlag

 Fecha de publicación: 01/02/2014

Nº de páginas: 38

Tipo de publicación: Artículo de Revista

 DOI: 10.1007/JHEP02(2014)088

ISSN: 1126-6708,1029-8479

Proyecto español: FPA2014-55295-C3-1-R ; FPA 2011-28694-C02-01

Url de la publicación: https://doi.org/10.1007/JHEP02(2014)088