Measurement of exclusive Ῠ photoproduction from protons in p Pb collisions at √{[b]{s_{NN}} = 5.02 {TeV}

The exclusive photoproduction of Ῠ (nS) meson states from protons, γ p → Ῠ (nS) p (with n=1,2,3), is studied in ultraperipheral p Pb collisions at a centre-of-mass energy per nucleon pair of √{[b]{s_{NN}} = 5.02 {TeV} . The measurement is performed using the Ῠ (nS) → μ ^+μ ^- decay mode, with data collected by the CMS experiment corresponding to an integrated luminosity of 32.6 {nb}^{-1}. Differential cross sections as functions of the Ῠ (nS) transverse momentum squared p_T ^2, and rapidity y, are presented. The Ῠ (1S) photoproduction cross section is extracted in the rapidity range |y |< 2.2, which corresponds to photon-proton centre-of-mass energies in the range 91<W_{γ p} <826 {GeV} . The data are compared to theoretical predictions based on perturbative quantum chromodynamics and to previous measurements.