Narrow Results

Final results of a detailed analysis of p+p elastic scattering data are presented, utilizing the quark–diquark model of protons in a form proposed by Bialas and Bzdak. The differential cross-section of elastic proton–proton collisions is analyzed in a detailed and systematic manner at small momentum transfers, starting from the energy range of CERN ISR at , including also recent TOTEM data at the present LHC energies at . These studies confirm the picture that the size of proton increases systematically with increasing energies, while the size of the constituent quarks and diquarks remains approximately independent of (or only increases slightly with) the colliding energy. The detailed analysis indicates correlations between model parameters and also indicates an increasing role of shadowing at LHC energies. Within the investigated class of models, a simple and model-independent phenomenological relation was discovered that connects the total p+p scattering cross-section to the effective quark, diquark size and their average separation. Our best fits indicate that the relative error of this phenomenological relation is 10–15% in the considered energy range.

We study high energy proton-proton (pp) elastic reactions in a meson-exchange model. The observed differential cross sections at small momentum exchanges (|t|<0.8 GeV²) are well reproduced for a large energy range (s~100 to 1000 GeV²) in the model. Our study reveals that the meson-exchange model developed in the low and medium energy sector is applicable to the high-energy pp elastic reactions. It might be argued that high-energy reactions at small momentum transfers might be as soft as low and medium energy processes.

The _{pp → p}ΛK⁺ and _{pp → p}Σ⁰K⁺ reactions near threshold are studied using the chiral unitary model. The single-pion and single-kaon exchanges are taken into account as well as the final state interactions of nucleon-hyperon, K-hyperon and K-nucleon systems. We calculate the total cross section of the _{pp → p}ΛK⁺ reaction which is consistent with the experimental data. We also calculate the total cross section of the _{pp → p}Σ⁰K⁺ reaction. Our result can explain the experimental observed strong suppression of Σ⁰ production compared to Λ production at the same excess energy.