$\varphi$-meson production at forward rapidity in p-Pb collisions at $\sqrt{s_{\mathrm{N}\mathrm{N}}}$ = 5.02 TeV and in pp collisions at $\sqrt{s}$ = 2.76 TeV

The first study of $\varphi$-meson production in p-Pb collisions at forward and backward rapidity, at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{\rm NN}} = 5.02$TeV,hasbeenperformedwiththeALICEapparatusattheLHC\mathrm{.}The$\phi$-mesons have been identified in the dimuon decay channel in the transverse momentum ($p_{\mathrm{T}}$) range $1<p_{\mathrm{T}}<7$ GeV/$c$, both in the p-going ($2.03<y<3.53$) and the Pb-going ($-4.46<y<-2.96$) directions, where $y$ stands for the rapidity in the nucleon-nucleon centre-of-mass, the integrated luminosity amounting to $5.01 \pm 0.19$nb$^{-1}$and$5.81 \pm 0.20$nb$^{-1}$, respectively, for the two data samples. Differential cross sections as a function of transverse momentum and rapidity are presented. The forward-backward ratio for $\varphi$-meson production is measured for $2.96<\mathrm{\mid }y\mathrm{\mid }<3.53$, resulting in a ratio $\sim 0.5$ with no significant $p_{\mathrm{T}}$ dependence within the uncertainties. The $p_{\mathrm{T}}$ dependence of the $\varphi$ nuclear modification factor $R_{\mathrm{p}\mathrm{P}\mathrm{b}}$ exhibits an enhancement up to a factor 1.6 at $p_{\mathrm{T}}$ = 3-4 GeV/$c$ in the Pb-going direction. The $p_{\mathrm{T}}$ dependence of the $\varphi$-meson cross section in pp collisions at $\sqrt{s}$ = 2.76 TeV, which is used to determine a reference for the p-Pb results, is also presented here for $1<p_{\mathrm{T}}<5$ GeV/$c$ and $2.5<y<4$ for a $78\pm 3$~nb${}^{-1}$ integrated luminosity sample.