ATLASmeasuredthe centrality dependence of the dijet yield using 165 nb−1 of p þ Pb data collected at f f iffiffiffiffiffiffiffi sNN p ¼8.16TeV in 2016. The event centrality, which reflects the pþPb 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 þ Pb collisions by covering parton momentum fractions from the valence region down to xp ∼10−3 and xPb ∼4×10−4.

Aad, G., Abbott, B., Abeling, K., Abicht, N. ., Abidi, S. ., Aboulhorma, A., et al. (2024). Measurement of the Centrality Dependence of the Dijet Yield in p+Pb Collisions at sNN=8.16  TeV with the ATLAS Detector. PHYSICAL REVIEW LETTERS, 132(10), 102301-1-102301-22 [10.1103/physrevlett.132.102301].

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

Alfonsi, F.;Ballabene, E.;Bellagamba, L.;Bianco, G.;Boscherini, D.;Bruni, A.;Carratta, G.;Cremonini, D.;De Castro, S.;Fabbri, F.;Fabbri, L.;Franchini, M.;Gabrielli, A.;Giacobbe, B.;Lasagni Manghi, F.;Massa, L.;Monzani, S.;