Quarkonia production in proton-lead collisions at LHCb

The production of $J/\psi$ and $\Upsilon (1S)$ mesons decaying into dimuon final state is studied at the LHCb experiment, with rapidity 1.5 $<$ y $<$ 4.0 or $-$5.0 $<$ y $< -2.5$ in proton-lead collisions at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{NN}} = 5 \,\mathrm{TeV} $, based on a data sample corresponding to an integrated luminosity of 1.6 nb$^{-1}$. The nuclear modification factor and forward-backward production ratio are determined for prompt $J/\psi$, $J/\psi$ from $b$-hadron decay and $\Upsilon(1S)$ mesons in study of the cold nuclear matter effects.