$\phi$ meson production in proton-proton collisions in the NA61/SHINE experiment at CERN SPS

This thesis presents results on $\phi$ meson production in p+p collisions at CERN SPS energies. They are derived from data collected by the NA61/SHINE experiment, by means of invariant mass spectra fits in $\phi \to K^+K^−$ decay channel, using the so-called tag-and-probe method to remove bias due to inefficiency of kaon candidates selection with dE/dx. These results include double differential spectra (first for $\phi$ mesons at CERN SPS energies) of rapidity y and transverse momentum $p_T$ for beam momenta of 158 GeV/c and 80 GeV/c, as well as singly differential spectra of y or $p_T$ for beam momentum of 40 GeV/c. Additionally, y spectra integrated over $p_T$ were obtained from double differential spectra. Also total $\phi$ yields were determined by integration and extrapolation of y spectra and widths of these spectra along with yields at y = 0 were calculated from fits of the distributions with Gaussian functions. Results were compared with world data on $\phi$ meson production in p+p collisions showing consistency and superior accuracy. They served also as reference for Pb+Pb data on $\phi$ production, confirming and emphasizing earlier findings regarding phenomena in Pb+Pb. Finally, results were also compared with model predictions showing that none of considered models could describe properly all observables.