Impact of the Nuclear Modification of the Gluon Densities on J/Psi production in pPb collisions at sqrt(sₙN) = 5 TeV

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We update our previous studies of nuclear-matter effects on J/Psi production in proton-nucleus for the recent LHC pPb runs at sqrt(sₙN)=5 TeV. We have analysed the effects of the modification of the gluon PDFs in nucleus, using an exact kinematics for a 2->2 process, namely g+g->J/Psi+g as expected from LO pQCD. This allows to constrain the transverse-momentum while computing the nuclear modification factor for different rapidities, unlike with the usual simplified kinematics. Owing to the absence of measurement in pp collisions at the same sqrt(sₙN) and owing to the expected significant uncertainties in yield interpolations which would hinder definite interpretations of nuclear modification factor --RₚPb--, we have derived forward-to-backward and central-to-peripheral yield ratios in which the unknown proton-proton yield cancel. These have been computed without and with a transverse-momentum cut, e.g. to comply with the ATLAS and CMS constraints in the central-rapidity region.