K*(892)$^{0}$ meson production in p+p collisions at the CERN SPS energies

This thesis presents K$^∗$(892)$^{0}$ meson measurements via $K$$^{+}$ π$^{−}$ decay channel for p+p interactions at 40–158 GeV/$c$ beam momenta. The data sets were recorded by the NA61/SHINE experiment located at the CERN Super Proton Synchrotron. For the first time, the K$^{∗}$(892)$^{0}$ signal was obtained based on the template method. This method was developed by the thesis author as an alternative to the known coctail fit method, which does not work properly for decay channels different than π$^{+}$ π$^{−}$ . The K$^{∗}$(892)$^{0}$ meson was studied in the K$^{+}$ π$^{−}$ decay channel and therefore the modification of the coctail fit method was needed. The analysis methodology is described in details in Chapter 4. The high statistics of data for p+p interactions at 158 GeV/c allowed to prepare the double-differential transverse momentum and rapidity spectra. For 158 GeV/c, the mean multiplicity of K$^{∗}$(892)$^{0}$ mesons was calculated based on the $pT$-integrated and extrapolated rapidity distribution. This value was compared with the Hadron Resonance Gas Models (HGM) as well as the EPOS 1.99 model. Previously published measurements of charged kaons were used to determine the K$^{∗}$(892)$^{0}$ to K^± multiplicity ratios, which allow to estimate time interval between chemical and kinetic freeze-outs. The obtained mass and width of K$^{∗}$(892)$^{0}$ mesons peak were presented and compared with the available world experimental data. Due to the lower statistics of 40 GeV/c and 80 GeV/c p+p data, the K$^{∗}$(892)$^{0}$ analysis for those two energies was performed in rapidity bins only, whereas the transverse momentum range was fixed on 0 < $pT$ < 1.5 GeV/$c$. The extrapolated rapidity distributions were used to obtain the mean multiplicities of K$^{∗}$(892)$^{0}$ mesons. The results were also compared with the HGM and EPOS 1.99 predictions. The analysis of the K$^{∗}$(892)$^{0}$ to K^± multiplicity ratios was also presented for lower beam momenta. More details about the results are presented in Chapter 5.