First measurement of the vertical bar t vertical bar-dependence of coherent J/psi photonuclear production

The ALICE Collaboration, S. Acharya, D. Adamova, D. J. Kim, F. Krizek, A. Onnerstad, J. E. Parkkila, Heidi Maria Rytkönen, Sami Räsänen, Oskari Antti Matti Saarimäki, M. Slupecki, W. H. Trzaska

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The first measurement of the cross section for coherent J/Psi photoproduction as a function of vertical bar t vertical bar, the square of the momentum transferred between the incoming and outgoing target nucleus, is presented. The data were measured with the ALICE detector in ultra-peripheral Pb-Pbcollisions at a centre-of-mass energy per nucleon pair root s(NN) = 5.02 TeV with the J/Psi produced in the central rapidity region vertical bar y vertical bar < 0.8, which corresponds to the small Bjorken-xrange (0.3 - 1.4) x 10(-3).

The measured vertical bar t vertical bar-dependence is not described by computations based only on the Pb nuclear form factor, while the photonuclear cross section is better reproduced by models including shadowing according to the leading-twist approximation, or gluon-saturation effects from the impact-parameter dependent Balitsky-Kovchegov equation. These new results are therefore a valid tool to constrain the relevant model parameters and to investigate the transverse gluonic structure at very low Bjorken- x. (C) 2021 The Author(s). Published by Elsevier B.V.

Original languageEnglish
Article number136280
JournalPhysics Letters B
Number of pages13
Publication statusPublished - 10 Jun 2021
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 114 Physical sciences

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