Coherent rho and J/psi photoproduction in ultraperipheral processes with electromagnetic dissociation of heavy ions at RHIC and LHC

TL;DR

The paper develops a Gribov-Glauber framework to predict coherent photoproduction of J/ψ and ρ mesons in ultraperipheral heavy-ion collisions at 2.76 TeV and 5.5 TeV, incorporating channel-specific electromagnetic dissociation with neutron emission. It distinguishes light- and heavy-vector-meson dynamics, uses generalized vector dominance for ρ production, and leading-twist gluon shadowing for J/ψ production to constrain small-x nuclear gluon densities. Compared with STAR data, ρ predictions show partial-channel discrepancies at RHIC energies, while J/ψ results reveal reduced cross sections due to gluon shadowing relative to non-shadowing models. The work emphasizes multi-channel, neutron-tagged UPC measurements as a robust probe of nuclear breakup dynamics and gluon PDFs at low x, guiding future RHIC/LHC analyses and theory.

Abstract

We present predictions for the J/psi and rho meson production in the heavy ion ultraperipheral collisions (UPC) for the current energy 2.76 TeV at the LHC. Both total cross sections and cross sections with the neutron emission from one or both nuclei are presented. We also analyse the RHIC rho meson photoproduction data and emphasize importance of these data to test the current model for nucleus break up in UPC.

Figures (7)

• Figure 1: Comparison of the calculated cross sections for $\rho$ photoproduction in the gold-gold UPC with the STAR experimental results.
• Figure 2: Calculated rapidity distributions for different channels in $\rho$ photoproduction in gold-gold UPC at RHIC.
• Figure 3: Calculated rapidity distributions for different channels in $\rho$ photoproduction in lead-lead UPC at LHC.
• Figure 4: Calculated rapidity distributions for different channels in $J/\psi$ photoproduction in gold-gold UPC at RHIC.
• Figure 5: Calculated rapidity distributions for different channels in $J/\psi$ photoproduction in lead-lead UPC at LHC.