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

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Azimuthal dihadron correlations of charged particles have been measured in PbPb collisions at s N N = 2.76 TeV 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.