Nuclear shadowing in photoproduction of ρ mesons in ultraperipheral nucleus collisions at RHIC and the LHC

We argue that with an increase of the collision energy, elastic photoproduction of ρ mesons on nuclei becomes affected by the significant cross section of photon inelastic diffraction into large masses, which results in the sizable inelastic nuclear shadowing correction to σ_γA→ρA and the reduced effective ρ-nucleon cross section. We take these effects into account by combining the vector meson dominance model, which we upgrade to include the contribution of high-mass fluctuations of the photon according to QCD constraints, and the Gribov-Glauber approximation for nuclear shadowing, where the inelastic nuclear shadowing is included by means of cross section fluctuations. The resulting approach allows us to successfully describe the data on elastic ρ photoproduction on nuclei in heavy ion UPCs in the 7 GeV<W_γp<46 GeV energy range and to predict the value of the cross section of coherent ρ photoproduction in Pb-Pb UPCs at sNN=5.02 TeV in Run 2 at the LHC, dσ_{PbPb→ρPbPb}(y=0)/dy=560±25 mb.