The prompt and non-prompt production cross-sections for the χ<inf>c1</inf> and χ<inf>c2</inf> charmonium states are measured in pp collisions at √s = 7TeV with the ATLAS detector at the LHC using 4.5 fb<sup>−1</sup> of integrated luminosity. The χ<inf>c</inf> states are reconstructed through the radiative decay χ<inf>c</inf> → J/ψγ (with J/ψ → μ<sup>+</sup>μ<sup>−</sup>) where photons are reconstructed from γ → e+e− conversions. The production rate of the χ<inf>c2</inf> state relative to the χ<inf>c1</inf> state is measured for prompt and non-prompt χ<inf>c</inf> as a function of J/ψ transverse momentum. The prompt χ<inf>c</inf> 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<inf>c</inf> decays. The fractions of χ<inf>c1</inf> and χ<inf>c2</inf> produced in b-hadron decays are also measured.
- Hadron-hadron scattering
ASJC Scopus subject areas
- Nuclear and High Energy Physics