Inclusive jet and charged hadron nuclear modification factors in PbPb collisions at 2.76 TeV with CMS

Abstract

Measurements are reported for charged hadron and inclusive jet transverse momentum ( p T ) spectra in pp and PbPb collisions at a nucleon–nucleon center-of-mass energy of 2.76 TeV with the CMS detector. These measurements make use of the high-statistics jet-triggered data recorded in 2011, including the total available PbPb luminosity of 150 μ b − 1 . Charged particles are reconstructed using an iterative algorithm and spurious high- p T tracks are suppressed by requiring appropriate energy deposits in the calorimeter system. Jets are reconstructed with the anti- k T algorithm, using combined information from tracking and calorimetry. The charged particle p T distributions are measured in the pseudorapidity range of | η | < 1 , and p T up to 100 GeV/ c . The jet p T distributions are measured in the pseudorapidity range of | η | < 2 , and p T from 100 to 300 GeV/ c . The nuclear modification factors, R AA , for charged hadrons and jets are presented as a function of p T and collision centrality. In the range p T = 5 – 10 GeV / c the charged hadron production in PbPb collisions is suppressed by up to a factor of seven, compared to the pp yield scaled by the number of incoherent nucleon–nucleon collisions. The charged hadron R AA increases at higher p T and approaches a value of approximately 0.5 in the range p T = 40 – 100 GeV / c for the most central collisions.