LHCb: Quarkonia production in $p$-­Pb collision at LHCb

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 pT < 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 1.6 nb$^{−1}$. The forward-backward production ratio and the nuclear modification factor are determined for $J/\psi$ and Y(1S). Indication of forward backward production asymmetry is observed. There is also an indication of $J/\psi$ and Y(1S)production suppression with respect to proton-proton collisions in forward region and anti-shadowing effect in backward region.