K +-meson production inpBe interactions atT p=2.9 GeV

The production ofK ⁺ andπ ⁺ mesons and protons inpBe collisions atT _p=2.9 GeV has been studied at the ITEP proton synchrotron. Ejectiles with a momentum ofp=545 MeV/c were observed under an emission angle ?=17°. The detectors which have been developed for the identification of kaons out of a six orders of magnitude more intense background of pions and protons are described. A cross-section ratio d²σ _K ⁺/dΩdp: d² σ _p /dΩdp: d²σ _p /dΩdp of (1±0.34):(85±1):(31±1) has been measured. Normalization with existing pion data yields an invariant differential cross sectionE·d³σ _K ⁺/d³ p=(3.1±1.2) mbGeV^?2c³sr^?1 and a total cross section of σ_tot(pBe)=(3.7±1.5) mb. These cross sections are compared with existing data and theoretical predictions. TheA dependence ofK ⁺ production in the few-GeV range is analyzed.     

Resonance model study of strangeness production in pp collisions

Results for the energy dependence of the elementary kaon production cross sections in proton-proton collisions are reported. Calculations are performed within an extended version of the resonance model which was used for the previous studies of elementary kaon production in pion-nucleon and pion-Δ collisions. Although the model treatment is within theempirical tree level (observed widths for the resonances are used), it is fully relativistic, and includes all relevant baryon resonances up to 2 GeV. One of the purposes of this study is to provide the results for the simulation codes of subthreshold kaon production in heavy ion collisions. This is the first, consistent study of the elementary kaon production reactions including both πB and BB (B = N,Δ) collisions on the same footing. Comparisons are made between the calculated results and the existing semi-empirical parametrizations which are widely used for the simulation codes, as well as the experimental data.     

Heavy meson production in proton-nucleus reactions with empirical spectral functions

We study the production of K ⁺, ρ, ω and ? mesons in p ⁺¹² C reactions on the basis of empirical spectral functions. The high momentum, high removal energy part of the spectral function is found to be negligible in all cases close to the absolute threshold. Furthermore, the two-step process (pN → π N N; π N → N + K ⁺, ρ,ω,?) dominates the cross section at threshold energies in line with earlier calculations based on the folding model.     

The pp→K<Superscript>+</Superscript><Emphasis Type="Italic">Σ</Emphasis><Superscript>+</Superscript>n cross-section from missing-mass spectra

We utilize existing inclusive data on K⁺-meson momentum spectra of the reaction pp→K ⁺ X at T _p = 2.3-2.85GeV to deduce total cross-sections for pp→K ⁺ Σ ⁺ n. The method used to extract those cross-sections is explained and discussed in detail. Our result for T _p = 2.85GeV is consistent with the data point from a direct measurement at the same beam energy. The cross-section obtained for T _p = 2.3GeV is with 13.7±2.3μb considerably smaller than the value found in a recent experiment by the COSY-11 Collaboration at a somewhat lower beam energy, indicating that the pp→K ⁺ Σ ⁺ n reaction cross-section could exhibit a rather unusual energy dependence.     

Pion-nucleon charge exchange amplitudes above 2 GeV

The amplitudes for the pion-nucleon charge exchange reaction of the Karlsruhe-Helsinki and the George-Washington-University partial-wave analyses are compared with those of a Regge-cut model with the aim to explore the possibility to provide high-energy constraints for theoretical baryon resonance analyses in the energy region above 2GeV.