Quarkonium production at ATLAS

The production of quarkonium is an important testing ground for QCD calculations. The J/psi and Upsilon production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC. Differential cross-sections are presented as a function of transverse momentum and rapidity. The fraction of J/psi produced in B-hadron decays is also measured and the differential cross-sections of prompt and non-prompt J/psi production determined separately. Measurements of the fiducial production crosssection of the Upsilon(1S) and observation of the chi(c,bJ) states are also discussed.