Measurement of the Relative Rate of Prompt χc0, χc1 and χc2 Production at √s = 7 TeV

Prompt production of charmonium χc0, χc1 and χc2 mesons is studied using proton-proton collisions at the LHC at a centre-of-mass energy of √s = 7 TeV. The χc mesons are identified through their decay to J/ψ γ, with J/ψ → μ+ μ− using photons that converted in the detector. A data sample, corresponding to an integrated luminosity of 1.0 fb^−1 collected by the LHCb detector, is used to measure the relative prompt production rate of χc1 and χc2 in the rapidity range 2.0 < y < 4.5 as a function of the J/ψ transverse momentum from 3 to 20 GeV/c. First evidence for χc0 meson production at a high-energy hadron collider is also presented.