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Coherent photoproduction of ρ0 vector mesons in ultra-peripheral Pb-Pb collisions at \( \sqrt{{\mathrm{s}}_{\mathrm{NN}}} \) = 5.02 TeV

A preprint version of the article is available at arXiv.

Abstract

Cross sections for the coherent photoproduction of ρ0 vector mesons in ultra-peripheral Pb-Pb collisions at \( \sqrt{{\mathrm{s}}_{\mathrm{NN}}} \) = 5.02 TeV are reported. The measurements, which rely on the π+π decay channel, are presented in three regions of rapidity covering the range |y| < 0.8. For each rapidity interval, cross sections are shown for different nuclear-breakup classes defined according to the presence of neutrons measured in the zero-degree calorimeters. The results are compared with predictions based on different models of nuclear shadowing. Finally, the observation of a coherently produced resonance-like structure with a mass around 1.7 GeV/c2 and a width of about 140 MeV/c2 is reported and compared with similar observations from other experiments.

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