Measurement of dijet pT correlations in Pb+Pb and pp collisions at √sNN = 2.76 TeV with the ATLAS detector

Measurements of dijets in both Pb+Pb and pp collisions at a nucleon--nucleon centre-of-mass energy of √sNN=2.76 TeV are presented. The measurements were performed with the ATLAS detector at the LHC using data samples with integrated luminosities of 0.14 nb−1 and 4.0 pb−1 for the Pb+Pb and pp data samples, respectively. Jets were reconstructed using the anti-ktkt algorithm with R=0.4. A background subtraction procedure was applied to correct the jet kinematics for the large underlying event present in Pb+Pb collisions. Measurements are reported of the normalized yields 1NdNdxJ, where xJ=pT2/pT1 and pT1 and pT2 are the leading and subleading jet transverse momenta, respectively. The results are presented as a function of pT1 and collision centrality. The results were obtained by measuring the two-dimensional pT1−pT2 distributions and applying an unfolding procedure to account for experimental resolution in the measurement of both jets' transverse momenta simultaneously. The distributions are found to be similar in peripheral Pb+Pb collisions and pp collisions, but highly modified in central Pb+Pb collisions. The results are consistent with expectations from partonic energy loss.