ϕ-Meson production at forward rapidity in p–Pb collisions at √sNN = 5.02 TeV and in pp collisions at √s = 2.76 TeV

The first study of φ-meson production in p–Pb collisions at forward and backward rapidity, at a nucleon– nucleon centre-of-mass energy √sNN = 5.02 TeV, has been performed with the ALICE apparatus at the LHC. The φ-mesons have been identified in the dimuon decay channel in the transverse momentum (pT) range 1 < pT < 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 ± 0.19 nb−1 and 5.81 ± 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 φ-meson production is measured for 2.96 < |y| < 3.53, resulting in a ratio ∼ 0.5 with no significant pT dependence within the uncertainties. The pT dependence of the φ nuclear modification factor RpPb exhibits an enhancement up to a factor 1.6 at pT = 3–4 GeV/c in the Pb-going direction. The pT dependence of the φ-meson cross section in pp collisions at √s = 2.76 TeV, which is used to determine a reference for the p–Pb results, is also presented here for 1 < pT < 5 GeV/c and 2.5 < y < 4, for a 78 ± 3 nb−1 integrated luminosity sample.