Quarkonium and heavy flavour production measurements at ATLAS

A large number of detailed measurements of various charm states production ($J/\psi, \psi(2S), \chi_c$) at the ATLAS experiment at the LHC at centre-of-mass energies of $2.76\,\mathrm{TeV}, 7\,\mathrm{TeV}, 8\,\mathrm{TeV}$, and $13\,\mathrm{TeV}$ is presented. These measurements extend in reach and precision beyond those currently available, and are compared to a variety of the latest theoretical predictions. Measurements of the associated production of quarkonium with a vector boson using the ATLAS Run-1 dataset are also presented. These rare processes provide new insight into QCD models of quarkonium production, but also provide new opportunities to study double parton scattering, including cross-section measurements in single and double parton scattering dominated regimes and a precise assessment of the $\sigma_\mathrm{eff}$ parameter governing the effective spatial area of parton--parton interactions at a variety of energy scales. Finally, latest results from the ATLAS experiment on heavy flavour production and decay properties at ATLAS are additionally presented. These results include determination of the decay properties of the $\Lambda_b$ baryon and new measurements of $B_c^+$ production cross-sections and branching ratio measurements of the $B_c^+\to J/\psi D^{*+}$ decay.