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arXiv · 2311.17611

Illuminating the impact-parameter dependence of UPC dijet photoproduction

Kari J. Eskola·Vadim Guzey·Ilkka Helenius·Petja Paakkinen·Hannu Paukkunen
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Abstract

We present new NLO pQCD predictions for photoproduction of dijets in ultraperipheral PbPb collisions at 5.02 TeV with a realistic photon flux and up-to-date nuclear PDFs. Our calculation of the impact parameter dependence of the photon flux includes the effects of the nuclear form factor in the photon-emitting nucleus and the spatial dependence of nuclear PDFs of the target nucleus, which are estimated using the Wood-Saxon nuclear density profile. We show that a significant portion of the measured dijets at large $z_\gamma$ originate from events with impact parameters of the order of a few nuclear radii, and that the cross section predictions therefore become sensitive to the modelling of the nuclear geometry and photon flux close to the source nucleus.

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Kari J. Eskola, Vadim Guzey, Ilkka Helenius, Petja Paakkinen, Hannu Paukkunen. 2023-11-29. Illuminating the impact-parameter dependence of UPC dijet photoproduction. https://arxiv.org/abs/2311.17611

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