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Sumit Basu (Lund University)

Sumit Basu

Postdoctoral Researcher

Sumit Basu (Lund University)

Energy dependence of coherent photonuclear production of J/ψ mesons in ultra-peripheral Pb-Pb collisions at √sNN = 5.02 TeV

Author

  • S. Acharya
  • S. Basu
  • P. Christiansen
  • J. Hansen
  • K.E. Iversen
  • O. Matonoha
  • A.F. Nassirpour
  • R. Nepeivoda
  • A. Ohlson
  • D. Silvermyr
  • J. Staa
  • V. Vislavicius
  • N. Zurlo
Show all

Summary, in English

The cross section for coherent photonuclear production of J/ψ is presented as a function of the electromagnetic dissociation (EMD) of Pb. The measurement is performed with the ALICE detector in ultra-peripheral Pb-Pb collisions at a centre-of-mass energy per nucleon pair of sNN = 5.02 TeV. Cross sections are presented in five different J/ψ rapidity ranges within |y| < 4, with the J/ψ reconstructed via its dilepton decay channels. In some events the J/ψ is not accompanied by EMD, while other events do produce neutrons from EMD at beam rapidities either in one or the other beam direction, or in both. The cross sections in a given rapidity range and for different configurations of neutrons from EMD allow for the extraction of the energy dependence of this process in the range 17 < Wγ Pb,n < 920 GeV, where Wγ Pb,n is the centre-of-mass energy per nucleon of the γPb system. This range corresponds to a Bjorken-x interval spanning about three orders of magnitude: 1.1 × 10 −5 < x < 3.3 × 10 −2. In addition to the ultra-peripheral and photonuclear cross sections, the nuclear suppression factor is obtained. These measurements point to a strong depletion of the gluon distribution in Pb nuclei over a broad, previously unexplored, energy range. These results, together with previous ALICE measurements, provide unprecedented information to probe quantum chromodynamics at high energies. [Figure not available: see fulltext.] © 2023, The Author(s).

Department/s

  • Particle and nuclear physics

Publishing year

2023

Language

English

Publication/Series

Journal of High Energy Physics

Volume

2023

Issue

10

Document type

Journal article

Publisher

Springer

Topic

  • Subatomic Physics

Keywords

  • Forward Physics
  • Heavy Ion Experiments
  • Quarkonium

Status

Published

ISBN/ISSN/Other

  • ISSN: 1029-8479