Work

Spatial resolution of dijet photoproduction in near-encounter ultraperipheral nuclear collisions

Year: 2024

Type: article

Abstract: We present next-to-leading order perturbative QCD predictions for inclusive dijet photoproduction in ultraperipheral nucleus-nucleus collisions (UPCs) within the impact-parameter dependent equivalent photon approximation. Taking into account the finite size of both the photon-emitting nucleus and the target nucleus, we show that this process is sensitive to the transverse-plane geometry of the UPC events. We show that this leads to a sizable, 20–40% effect for large values of the z γ variable in the dijet photoproduction cross section in lead-lead UPCs at 5.02 TeV compared to the widely used pointlike approximation where the nuclear radius is accounted for only as a sharp cutoff in the photon flux calculation. This resolution of the spatial degrees of freedom is a result of having high-transverse-momentum jets in the final state, which at the large- z γ kinematics requires a highly energetic photon in the initial state, thus biasing the collisions to small impact-parameter “near-encounter” configurations. We further discuss the role of the forward-neutron event-class selection in isolating the photonuclear cross section in the nucleus-nucleus collisions, and employ the needed electromagnetic breakup survival factor in our predictions. Published by the American Physical Society 2024

Source: Physical Review C

DOI: 10.1103/physrevc.110.054906

Authors: Kari J. Eskola, Vadim Guzey, Ilkka Helenius, Petja Paakkinen, Hannu Paukkunen

Institutions: University of Helsinki, Helsinki Institute of Physics, University of Jyväskylä

Language: English

Topic: High-Energy Particle Collisions Research

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Funders: Academy of Finland, China Scholarship Council, CSC – IT Center for Science, H2020 European Research Council