Search for the Jet-Induced Diffusion Wake in the Quark-Gluon Plasma via Measurements of Jet-Track Correlations in Photon-Jet Events in Pb Plus Pb Collisions at √Snn=5.02 TeV With the Atlas Detector

Abstract

This paper presents a measurement of jet-track correlations in photon-jet events, using 1.72 nb(-1) of Pb+Pb data at root s(NN) = 5.02 TeV recorded with the ATLAS detector at the LHC. Events with energetic photon-jet pairs are selected, where the photon and jet are approximately back-to-back in azimuth. The angular correlation between jets and charged-particle tracks with transverse momentum (p(T)) in the range 0.5-2.0 GeV in the hemisphere opposite to the jet, |Delta phi(jet,track)| > pi/2, is measured as a function of their relative pseudorapidity difference, |Delta eta(jet,track)|. In central Pb+Pb collisions, these correlations are predicted to be sensitive to the diffusion wake in the quark-gluon plasma resulting from the lost energy of high-p(T) partons traversing the plasma, with a characteristic modification as a function of |Delta eta(jet,track)|. The correlations are examined with different selections on the jet-to-photon p(T) ratio to select events with different degrees of energy loss. No diffusion wake signal is observed within the current sensitivity and upper limits at 95% confidence level on the diffusion wake amplitude are reported.