Measurements of the production of P-wave charmonium states through radiative decays at the ATLAS experiment

Institute of Physics ASCR Prague

^a e-mail: marcisov@fzu.cz

Published online: 29 April 2014

Abstract

The production cross sections of the χ_c1 and χ_c2 charmonium states are measured in pp collisions at √s = 7 TeV using 4.5 fb⁻¹ of integrated luminosity recorded by the ATLAS detector at the LHC. The χ_c states are reconstructed via the radiative decay χ_c → J/ψ(μ⁺μ⁻)γ, where the photons are reconstructed using γ → e⁺ e⁻ conversion in the detector material. Differential production cross sections for prompt and non-prompt χ_c1,2 are presented, as well as the fraction of inclusive J/ψ produced by feed-down from the χ_c states. The results are compared with a range of theoretical predictions. The branching fraction of ℬ (B⁺ → χ_c1K⁺) is measured using the same dataset and χ_c event selection.