Production of φ-mesons in p + p, p + Pb and central Pb + Pb collisions at Ebeam=158 A GeV

Yields and phase space distributions of phi -mesons emitted from p + p (minimum bias trigger), p + Pb (at various centralities) and central Pb + Pb collisions are reported (E-beam = 158 A GeV). The decay phi --> K+K- was used for identification. The phi/pi ratio is found to increase by a factor of 3.0 +/- 0.7 from inelastic p + p to central Pb + Pb. Significant enhancement in this ratio is also observed in subclasses of p + p events (characterized by high charged-particle multiplicity) as well as in the forward hemisphere of central p + Pb collisions. In Pb + Pb no shift or significant broadening of the phi -peak is seen. (C) 2000 Published by Elsevier Science B.V.