Measurements of inclusive spectra and mean multiplicities of π ± , K ± , p andp produced in inelastic p + p interactions at incident projectile momenta of 20,31,40, 80 and 158 GeV/c ( √ s = 6.3, 7.7, 8.8, 12.3 and 17.3 GeV, respectively) were performed at the CERN Super Proton Synchrotron using the large acceptance NA61/SHINE hadron spectrometer. Spectra are presented as function of rapidity and transverse momentum and are compared to predictions of current models. The measurements serve as the baseline in the NA61/SHINE study of the properties of the onset of deconfinement and search for the critical point of strongly interacting matter.

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The measurement of K * (892) 0 resonance production via its K + π − decay mode in inelastic p+p collisions at beam momentum 158 GeV/c (√ s N N = 17.3 GeV) is presented. The data were recorded by the NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The template method was used to extract the K * (892) 0 signal and double-differential transverse momentum and rapidity spectra were obtained. The full phase-space mean multiplicity of K * (892) 0 mesons was found to be (78.44 ± 0.38(stat) ± 6.0(sys)) • 10 −3. The NA61/SHINE results are compared with the Epos1.99 and Hadron Resonance Gas models as well as with world data from p+p and nucleus-nucleus collisions.

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 p T for proton beam momenta of 80 GeV/c and 158 GeV/c, as well as single differential spectra of y or p T 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.

We present measurements of ρ 0 , ω and K * 0 spectra in π − + C production interactions at 158 GeV/c and ρ 0 spectra at 350 GeV/c using the NA61/SHINE spectrometer at the CERN SPS. Spectra are presented as a function of the Feynman's variable x F in the range 0 < x F < 1 and 0 < x F < 0.5 for 158 and 350 GeV/c respectively. Furthermore, we show comparisons with previous measurements and predictions of several hadronic interaction models. These measurements are essential for a better understanding of hadronic shower development and for improving the modeling of cosmic ray air showers.