ϒ suppression at forward rapidity in Pb–Pb collisions at √sNN=5.02 TeV

Abstract

Inclusive ϒ(1S) and ϒ(2S) production have been measured in Pb–Pb collisions at the centre-of-mass energy per nucleon–nucleon pair √sNN = 5.02TeV, using the ALICE detector at the CERN LHC. The ϒmesons are reconstructed in the centre-of-mass rapidity interval 2.5 < y < 4 and in the transverse-momentum range pT < 15 GeV/c, via their decays to muon pairs. In this Letter, we present results on the inclusive ϒ(1S) nuclear modification factor RAAas a function of collision centrality, transverse momentum and rapidity. The ϒ(1S) and ϒ (2S) RAA, integrated over the centrality range 0 – 90 %, are 0.37 ± 0.02 (stat) ± 0.03 (syst) and 0.10 ± 0.04 (stat) ± 0.02 (syst), respectively, leading to a ratio Rϒ(2S) AA/Rϒ(1S) AAof 0.28 ± 0.12 (stat) ± 0.06(syst). The observed ϒ(1S) suppression increases with the centrality of the collision and no significant variation is observed as a function of transverse momentum and rapidity.