Regular Article - Theoretical Physics
nNNPDF3.0: evidence for a modified partonic structure in heavy nuclei
Department of Physics and Astronomy, VU Amsterdam, 1081 HV, Amsterdam, The Netherlands
2 Nikhef Theory Group, Science Park 105, 1098 XG, Amsterdam, The Netherlands
3 Physikalisches Institut, University of Bonn, 53115, Bonn, Germany
4 The Higgs Centre for Theoretical Physics, University of Edinburgh, JCMB, KB, Mayfield Rd, EH9 3JZ, Edinburgh, Scotland, UK
5 Tif Lab, Dipartimento di Fisica, Università di Milano, and INFN, Sezione di Milano, Via Celoria 16, 20133, Milan, Italy
Accepted: 10 May 2022
Published online: 3 June 2022
We present an updated determination of nuclear parton distributions (nPDFs) from a global NLO QCD analysis of hard processes in fixed-target lepton-nucleus and proton-nucleus together with collider proton-nucleus experiments. In addition to neutral- and charged-current deep-inelastic and Drell–Yan measurements on nuclear targets, we consider the information provided by the production of electroweak gauge bosons, isolated photons, jet pairs, and charmed mesons in proton-lead collisions at the LHC across centre-of-mass energies of 5.02 TeV (Run I) and 8.16 TeV (Run II). For the first time in a global nPDF analysis, the constraints from these various processes are accounted for both in the nuclear PDFs and in the free-proton PDF baseline. The extensive dataset underlying the nNNPDF3.0 determination, combined with its model-independent parametrisation, reveals strong evidence for nuclear-induced modifications of the partonic structure of heavy nuclei, specifically for the small-x shadowing of gluons and sea quarks, as well as the large-x anti-shadowing of gluons. As a representative phenomenological application, we provide predictions for ultra-high-energy neutrino-nucleon cross-sections, relevant for data interpretation at neutrino observatories. Our results provide key input for ongoing and future experimental programs, from that of heavy-ion collisions in controlled collider environments to the study of high-energy astrophysical processes.
© This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2022
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