Measurement of χ c1 and χ c2 production with s √s = 7 TeV pp collisions at ATLAS

The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at √ s = 7 TeV with the ATLAS detector at the LHC using 4.5 fb -1 of integrated luminosity.The χ c states are reconstructed through the radiative decay χ c → J/ψ γ (with J/ψ → µ + µ -) where photons are reconstructed from γ → e + e -conversions.The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum.The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays.The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured.