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

The ATLAS Collaboration  ,  Hara, K.  ,  Kim, S.H.  ,  Okawa, H.  ,  Sato, K.  ,  Ukegawa, F.

774pp.379 - 402 , 2017-11 , Elsevier
Measurements of dijet PT correlations in Pb+Pb and pp collisions at a nucleon–nucleon centre-of-mass energy of √sNN = 2.76TeV are presented. The measurements are performed with the ATLAS detector at the Large Hadron Collider using Pb + Pb and pp data samples corresponding to integrated luminosities of 0.14nb-1and 4.0pb-1, respectively. Jets are reconstructed using the anti-Kt algorithm with radius parameter values R = 0.3 and R=0.4. A background subtraction procedure is applied to correct the jets for the large underlying event present in Pb + Pb collisions. The leading and sub-leading jet transverse momenta are denoted PT1 and PT2. An unfolding procedure is applied to the two-dimensional (PT1, PT2) distributions to account for experimental effects in the measurement of both jets. Distributions of (1/N)dN/dxj, where xj = pT2 /pT1 , are presented as a function of Pt1 and collision centrality. The distributions are found to be similar in peripheral Pb + Pb collisions and pp collisions, but highly modified in central Pb + Pb collisions. Similar features are present in both the R = 0.3 and R = 0.4 results, indicating that the effects of the underlying event are properly accounted for in the measurement. The results are qualitatively consistent with expectations from partonic energy loss models.

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