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The differential production cross sections of K + and K − mesons have been measured at the ITEP proton synchrotron in p + Be, p + Cu collisions under lab angle of 10.5 • , respectively, at 1.7 and 2.25, 2.4 GeV beam energies. A detailed comparison of these data with the results of calculations within an appropriate folding model for incoherent primary proton-nucleon, secondary pion-nucleon kaon and antikaon production processes and processes associated with the creation of antikaons via the decay of intermediate phi mesons is given. We show that the strangeness exchange process Y N → N N K − gives a small contribution to the antikaon yield in the kinematics of the performed experiment. We argue that in the case when antikaon production processes are dominated by the channels with KK − in the final state, the cross sections of the corresponding reactions are weakly influenced by the in-medium kaon and antikaon mean fields.

Yields of K + and K − mesons from proton-nucleus collisions at the subthreshold energy range were measured. Kaons produced at 10.5 • with momentum 1.28 GeV/c were detected by a beam-line focusing hadron spectrometer (FHS). The parameters of the Folding model were fixed by the best fit to the K + data. Calculation with normal antikaon mass underestimates the experimental cross section of K − production by a factor of 2.5. In-medium antikaon mass was found to be 0.6-0.85 of its vacuum mass depending on the parametrization of the total cross section for K − production in pN collisions.

Inclusive cross sections σ A = Ed 3 σ(X, P 2 t )/d 3 p of antiproton and negative pion production on Be, Al, Cu and Ta targets hit by 10 GeV protons were measured at the laboratory angles of 10.5• and 59• . Antiproton cross sections were obtained in both kinematically allowed and kinematically forbidden regions for antiproton production on a free nucleon. The antiproton cross section ratio as a function of the longitudinal variable X exhibits three separate plateaus which gives evidence for the existence of compact baryon configurations in nuclei-small-distance scaled objects of nuclear structure. Comparability of the measured cross section ratios with those obtained in the inclusive electron scattering off nuclei suggests a weak antiproton absorption in nuclei. Observed behavior of the cross section ratios is interpreted in the framework of a model considering the hadron production as a fragmentation of quarks (antiquarks) into hadrons. It has been established that the antiproton formation length in nuclear matter can reach the magnitude of 4.5 fm.