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 $\sqrt{s} = 7$~TeV, using the ATLAS detector at the LHC. These include the production cross sections of the $C$-even states $\chi_{c1}$ and $\chi_{c2}$ in their radiative decay modes into $J/\psi \gamma$, and of the radially excited vector state $\psi(2S)$ in its decay mode into $J/\psi \pi^+ \pi^-$. 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.