Suppression of inclusive J/$\mathbf{\psi}$ and $\mathbf{\psi}$(2S) production in p-Pb collisions with ALICE at the LHC

The ALICE Collaboration has studied inclusive J/$\psi$ and $\psi$(2S) production in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV with the Muon Spectrometer. The measurement was performed at forward (2.03 $<$ $y_{\rm cms}$ $<$ 3.53) and backward ($-$4.46 $<$ $y_{\rm cms}$ $<$ $-$2.96) centre of mass rapidities. The nuclear modification factor of J/$\psi$ and $\psi$(2S) has been measured as a function of transverse momentum and event activity. Theoretical models based on nuclear shadowing, coherent energy loss or both are in reasonable agreement with the J/$\psi$ results but cannot describe the $\psi$(2S) behaviour. Other mechanisms must be invoked in order to explain the $\psi$(2S) suppression in p-Pb collisions.