Measurement of the relative prompt production rate of chi(c2) and chi(c1) in $pp$ collisions at $\sqrt{s}=7$ TeV

A measurement is presented of the relative prompt production rate of χ c2 and χ c1 with 4.6 fb−1 of data collected by the CMS experiment at the LHC in pp collisions at TeX . The two states are measured via their radiative decays χ c→J/ψ+γ, with the photon converting into an e+e− pair for J/ψ rapidity |y(J/ψ)| 0.5 GeV/c. The measurement is given for six intervals of p T(J/ψ) between 7 and 25 GeV/c. The results are compared to theoretical predictions.