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

Abstract

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 m T 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.