Measurement of φ meson production in p + p interactions at 40 , 80 and 158 GeV / c with the NA 61 / SHINE spectrometer at the CERN SPS NA 61 / SHINE Collaboration

Results on φ meson production in inelastic p+ p collisions at CERN SPS energies are presented. They are derived from data collected by the NA61/SHINE fixed target experiment, by means of invariant mass spectra fits in the φ → K+K− decay channel. They include the first ever measured double differential spectra of φ mesons as a function of rapidity y and transverse momentum pT for proton beam momenta of 80 GeV/c and 158 GeV/c, as well as single differential spectra of y or pT for beam momentum of 40 GeV/c. The corresponding total φ yields per inelastic p + p event are obtained. These results are compared with existing data on φ meson production in p + p collisions. The comparison shows consistency but superior accuracy of the present measurements. The emission of φ mesons in p + p reactions is confronted with that occurring in Pb + Pb collisions, and the experimental results are compared with model predictions. It appears that none of the considered models can properly describe all the experimental observations.