European Physical Journal C, vol.72, no.12, pp.1-22, 2012 (SCI-Expanded)
A measurement is presented of the relative prompt production rate of χc2 and χc1 with 4.6 fb-1 of data collected by the CMS experiment at the LHC in pp collisions at √s = 7 TeV. The two states are measured via their radiative decays χc→J/ψ+γ, with the photon converting into an e+e- pair for J/ψ rapidity {pipe}y(J/ψ){pipe}<1.0 and photon transverse momentum pT(γ)>0.5 GeV/c. The measurement is given for six intervals of pT(J/ψ) between 7 and 25 GeV/c. The results are compared to theoretical predictions. © 2012 CERN for the benefit of the CMS collaboration.