NA60 results on ϕ production in the hadronic and leptonic channels in In-In collisions at 158 GeV Original Research Article

The NA60 experiment at the CERN SPS studied ϕ meson production in In-In collisions at 158 A GeV via muon and kaon decay channels. Results in the hadronic channel are presented for the first time. These are discussed in the framework of the so-called ϕ puzzle through the comparison with the previous NA60 measurements in the muon channel. The yield and inverse mT slopes observed in the two channels are compatible within errors, showing that the large discrepancies seen in Pb-Pb collisions between NA50 (muon pairs) and NA49 (kaon pairs) are not seen in the NA60 In-In data.