ATLAS results on heavy flavour production and its relation to quark matter

We present measurements of $J/\psi$ and $\psi$(2S) production in proton-lead collisions at a centre of mass energy per nucleon-nucleon interaction of 5.02 TeV, and in proton-proton collisions at 2.76 TeV, with integrated luminosities of 28.1~$nb^{-1}$ and 4.0~$pb^{-1}$, respectively . Both measurements are based on data recorded by the ATLAS detector in 2013 and are performed in the dimuon decay channel. Prompt components of $J/\psi$ and $\psi$(2S) are separated from the nonprompt components resulting from $b$-hadron decays through an analysis of the distance between the $J/\psi$ and $\psi$(2S) decay vertexes and the event primary vertex. The measurements of nuclear modification factors and self-normalized yields for the $J/\psi$ and $\psi$(2S) are performed in the following ranges: $8.5 < p_{T}^{\mu\mu} < 30$ GeV in transverse momentum, $-1.5 < y^*_{\mu\mu} < 1.5$ in centre-of-mass rapidity and $0-90\%$ in centrality. The differential cross-section for production of nonprompt $J/\psi$ is compared to a FONLL calculation that does not include nuclear effects for the ranges of $8 < p_{T}^{\mu\mu} < 30$ GeV in transverse momentum, and for $|y^*|_{\mu\mu} < 1.94$ in centre-of-mass rapidity. Forward-backward production ratios are presented and compared to theoretical predictions.