J/ψ suppression at forward rapidity in Pb–Pb collisions at sNN=5.02 TeV

The inclusive J/ψ production has been studied in Pb–Pb and pp collisions at the centre-of-mass energy per nucleon pair View the MathML sourcesNN=5.02 TeV, using the ALICE detector at the CERN LHC. The J/ψ meson is reconstructed, in the centre-of-mass rapidity interval 2.5<y<42.5<y<4 and in the transverse-momentum range pT<12 GeV/cpT<12 GeV/c, via its decay to a muon pair. In this Letter, we present results on the inclusive J/ψ cross section in pp collisions at View the MathML sources=5.02 TeV and on the nuclear modification factor RAARAA. The latter is presented as a function of the centrality of the collision and, for central collisions, as a function of the transverse momentum pTpT of the J/ψ . The measured RAARAA values indicate a suppression of the J/ψ in nuclear collisions and are then compared to our previous results obtained in Pb–Pb collisions at View the MathML sourcesNN=2.76 TeV. The ratio of the RAARAA values at the two energies is also computed and compared to calculations of statistical and dynamical models. The numerical value of the ratio for central events (0–10% centrality) is 1.17±0.04(stat)±0.20(syst)1.17±0.04(stat)±0.20(syst). In central events, as a function of pTpT, a slight increase of RAARAA with collision energy is visible in the region 2<pT<6 GeV/c2<pT<6 GeV/c. Theoretical calculations qualitatively describe the measurements, within uncertainties.