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

Abstract

The exclusive photoproduction of ϓ(nS) meson states from protons, γ p → 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 = 5.02 TeV. 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 32.6 nb⁻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 < 826 GeV. The data are compared to theoretical predictions based on perturbative quantum chromodynamics and to previous measurements.