op: differential φ meson production cross section d2σ /dydpT as a function of pT at √s = 5.02 TeV (left), √s = 8 TeV (center) and √s = 13 TeV (right) in the rapidity interval 2.5 < y < 4, compared with EPOS 3 [8–10], PHOJET [6, 7] and the Monash 2013 tune of PYTHIA 8.1 [1]. The boxes represent the systematic uncertainties, the error bars the statistical uncertainties. Bottom: ratio between the measured cross section and the calculations.