First measurement of the |t|-dependence of coherent J/ψ photonuclear production

Summary, in English

The first measurement of the cross section for coherent J/ψ photoproduction as a function of |t|, 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–Pb collisions at a centre-of-mass energy per nucleon pair sNN=5.02TeV with the J/ψ produced in the central rapidity region |y|<0.8, which corresponds to the small Bjorken-x range (0.3−1.4)×10−3. The measured |t|-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. © 2021 The Author(s)

• Author: S Acharya; Jonatan Adolfsson; Sumit Basu; Peter Christiansen; Oliver Matonoha; Adrian Nassirpour; Alice Ohlson; Anders Oskarsson; Tuva Richert; Omar Vazquez Rueda; David Silvermyr; N Zurlo
• Department/s: Particle and nuclear physics; eSSENCE: The e-Science Collaboration
• Publishing year: 2021
• Language: English
• Publication/Series: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
• Volume: 817
• Links: http://dx.doi.org/10.1016/j.physletb.2021.136280
• Document type: Journal article
• Publisher: Elsevier
• Topic: Subatomic Physics
• Status: Published
• ISBN/ISSN/Other: ISSN: 0370-2693