Production of quarkonium states at the ATLAS experiment

An overview is given of recent measurements of the production of various heavy quarkonium states in pp collisions at √s = 7 TeV, using the ATLAS detector at the LHC. These include the production cross sections of the C-even states χ_c1 and χ_c2 in their radiative decay modes into J/ψγ, and of the radially excited vector state ψ(2S) in its decay mode into J/ψπ⁺π⁻. Differential spectra in transverse momentum are measured separately for promptly produced charmonium states, originating from QCD sources, and for non-prompt states from the decays of B-hadrons. Results are compared to other existing measurements and various theoretical models.