Measurement of the Centrality Dependence of the Dijet Yield in p plus Pb Collisions at √sNN=8.16 TeV with the ATLAS Detector

Abstract

<p>ATLAS measured the centrality dependence of the dijet yield using 165 nb−1 of 𝑝+Pb data collected at √𝑠NN=8.16 TeV in 2016. The event centrality, which reflects the 𝑝+Pb impact parameter, is characterized by the total transverse energy registered in the Pb-going side of the forward calorimeter. The central-to-peripheral ratio of the scaled dijet yields, 𝑅CP, is evaluated, and the results are presented as a function of variables that reflect the kinematics of the initial hard parton scattering process. The 𝑅CP shows a scaling with the Bjorken 𝑥 of the parton originating from the proton, 𝑥𝑝, while no such trend is observed as a function of 𝑥Pb. This analysis provides unique input to understanding the role of small proton spatial configurations in 𝑝+Pb collisions by covering parton momentum fractions from the valence region down to 𝑥𝑝∼10−3 and 𝑥Pb∼4×10−4.<span> </span></p>