Production of $J/\psi$ and $\Upsilon$-mesons in proton-lead collisions at $\sqrt{s_{NN}}$ = 5 TeV

The production of $J/\psi$ and $\Upsilon$-mesons decaying into dimuon final state is studied at the LHCb experiment, with rapidity 1.5 < y < 4.0 or 5.0 < y < 2.5 and transverse momentum $p_T$ < 15 GeV/$c$, in proton-lead collisions at a proton-nucleon centre-of-mass energy $\sqrt{s_{NN}}$ = 5 TeV. The analysis is based on a data sample corresponding to an integrated luminosity of 16 nb$^{-1}$. The nuclear modification factor and the forward-backward production ratio are determined for $J/\psi$ and $\Upsilon(1S )$ mesons. At large rapidity clear suppression of prompt $J/\psi$ production is observed with respect to the production in $pp$ collisions, while the suppression of $J/\psi$ from $b$-hadron decays is less pronounced. The nuclear modification factor for $\Upsilon(1S )$mesons in the forward region is found to be similar to those for $J/\psi$ from b-hadron decays, and there is an indication of antishadowing effect in the backward region.