Measurement of the Azimuthal Angle Dependence of Inclusive Jet Yields in Pb +Pb Collisions at √sNN=2.76 TeV with the ATLAS Detector

Abstract

Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, 𝛥⁢𝜙, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the 𝛥⁢𝜙 dependence of jet yields in 0.14 nb−1 of √𝑠𝑁𝑁 =2.76 TeV Pb +Pb collisions at the LHC for jet transverse momenta 𝑝𝑇 >45 GeV in different collision centrality bins using an underlying event subtraction procedure that accounts for elliptic flow. The variation of the jet yield with 𝛥⁢𝜙 was characterized by the parameter, 𝑣jet2, and the ratio of out-of-plane (𝛥⁢𝜙 ∼𝜋/2) to in-plane (𝛥⁢𝜙 ∼0) yields. Nonzero 𝑣jet2 values were measured in all centrality bins for 𝑝𝑇 <160 GeV. The jet yields are observed to vary by as much as 20% between in-plane and out-of-plane directions.