Measurement of the jet radius and transverse momentum dependence of inclusive jet suppression in lead–lead collisions at √sNN=2.76 TeV with the ATLAS detector

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to
the physics of jet quenching. In a sample of lead–lead collisions at
√
sNN = 2.76 TeV corresponding to an
integrated luminosity of approximately 7 μb−1, ATLAS has measured jets with a calorimeter system over
the pseudorapidity interval |η| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets
were reconstructed using the anti-kt algorithm with values for the distance parameter that determines
the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is
characterized by the jet “central-to-peripheral ratio,” RCP. Jet production is found to be suppressed by
approximately a factor of two in the 10% most central collisions relative to peripheral collisions. RCP
varies smoothly with centrality as characterized by the number of participating nucleons. The observed
suppression is only weakly dependent on jet radius and transverse momentum. These results provide the
first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.