$\mathrm{{\rm Y}}$ suppression at forward rapidity in Pb-Pb collisions at $\sqrt{s_{\mathrm{N}\mathrm{N}}}$ = 5.02 TeV

Inclusive $\mathrm{{\rm Y}}$(1S) and $\mathrm{{\rm Y}}$(2S) production have been measured in Pb-Pb collisions at the centre-of-mass energy per nucleon-nucleon pair $\sqrt{s_{{}_{\mathrm{N}\mathrm{N}}}}=5.02$ TeV, using the ALICE detector at the CERN LHC. The $\mathrm{{\rm Y}}$ mesons are reconstructed in the centre-of-mass rapidity interval $2.5<y<4$ and in the transverse-momentum range $p_{\mathrm{T}}<15$ GeV/$c$, via their decays to muon pairs. In this Letter, we present results on the inclusive $\mathrm{{\rm Y}}$(1S) nuclear modification factor $R_{\mathrm{A}\mathrm{A}}$ as a function of collision centrality, transverse momentum and rapidity. The $\mathrm{{\rm Y}}$(1S) and $\mathrm{{\rm Y}}$(2S) $R_{\mathrm{A}\mathrm{A}}$, integrated over the centrality range 0-90%, are $0.37\pm 0.02(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t})\pm 0.03(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})$ and $0.10 \pm 0.04 {\rm{(stat)}}\pm 0.02 {\rm{(syst)}}$,respectively,leadingtoaratio$R_{\rm{AA}}^{\Upsilon(\rm2S)}/R_{\rm{AA}}^{\Upsilon(\rm1S)}$of$0.28\pm0.12$\text{(stat)}$\pm0.06$\text{(syst)}$$\mathrm{.}Theobserved$\Upsilon$(1S) suppression increases with the centrality of the collision and no significant variation is observed as a function of transverse momentum and rapidity.