Probing Small Bjorken-x Nuclear Gluonic Structure via Coherent J=ψ Photoproduction in Ultraperipheral Pb-Pb Collisions at √sNN = 5.02 TeV

Tumasyan A., Adam W., Andrejkovic J., Bergauer T., Chatterjee S., Damanakis K., ...More

Physical Review Letters, vol.131, no.26, 2023 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 131 Issue: 26
  • Publication Date: 2023
  • Doi Number: 10.1103/physrevlett.131.262301
  • Journal Name: Physical Review Letters
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Chemical Abstracts Core, Compendex, INSPEC, zbMATH, DIALNET
  • Yıldız Technical University Affiliated: No


Quasireal photons exchanged in relativistic heavy ion interactions are powerful probes of the gluonic structure of nuclei. The coherent J=ψ photoproduction cross section in ultraperipheral lead-lead collisions is measured as a function of photon-nucleus center-of-mass energies per nucleon (WPbγN) over a wide range of 40 < WPbγN < 400 GeV. Results are obtained using data at the nucleon-nucleon center-of-mass energy of 5.02 TeV collected by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 1.52 nb−1. The cross section is observed to rise rapidly at low WPbγN, and plateau above WPbγN ≈ 40 GeV, up to 400 GeV, entering a new regime of small Bjorken-x (≈6 × 10−5) gluons being probed in a heavy nucleus. The observed energy dependence is not predicted by current quantum chromodynamic models.