Measurement of the Production of Neighbouring Jets in Lead-Lead Collisions at √s̅_{NN}} = 2.76 TeV with the ATLAS Detector

This Letter presents measurements of correlated production of nearby jets in Pb+Pb collisions at √s̅_(NN) = 2.76 TeV using the ATLAS detector at the Large Hadron Collider. The measurement was performed using 0.14 nb⁻¹of data recorded in 2011. The production of correlated jet pairs was quantified using the rate, R_{ΔR}, of "neighbouring" jets that accompany "test" jets within a given range of angular distance, ΔR, in the pseudorapidity-azimuthal angle plane. The jets were measured in the ATLAS calorimeter and were reconstructed using the anti-k_t algorithm with radius parameters d = 0.2, 0.3, and 0.4. R_{ΔR} was measured in different Pb+Pb collision centrality bins, characterized by the total transverse energy measured in the forward calorimeters. A centrality dependence of R_{ΔR} is observed for all three jet radii with R_{ΔR} found to be lower in central collisions than in peripheral collisions. The ratios formed by the R_{ΔR} values in different centrality bins and the values in the 40-80% centrality bin are presented.