Measurement of exclusive Υ photoproduction from protons in pPb collisions at √sNN = 5.02TeV

Abstract

The exclusive photoproduction of Υ(nS) meson states from protons, γp→Υ(nS)p (with n=1,2,3), is studied in ultraperipheral pPb collisions at a centre-of-mass energy per nucleon pair of sNN−−−√=5.02TeV. The measurement is performed using the Υ(nS)→μ+μ− decay mode, with data collected by the CMS experiment corresponding to an integrated luminosity of 32.6nb−1. Differential cross sections as functions of the Υ(nS) transverse momentum squared p2T, and rapidity y, are presented. The Υ(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<Wγp<826GeV. The data are compared to theoretical predictions based on perturbative quantum chromodynamics and to previous measurements.