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In the past decades, considerable advances have been made both in experimentally studying and in theoretically describing properties of cold nuclear matter at short nucleon-nucleon distances. In the present study, it is shown that, in addition to the commonly known method of studying the structure of nuclei at short distances in processes of deep-inelastic lepton scattering, processes of particle production in nucleus-nucleus reactions beyond the kinematics of nucleon-nucleon collisions are an important complementary source of information. Some predictions concerning the behavior of special features that are peculiar to such processes and which one can extract from experimental data obtained for collisions of gold nuclei at an energy of 2.4 GeV in the HADES experiment at the GSI (Gemeinschaft für Schwerionenforschung) research center (Darmstadt, Germany) are presented. [ABSTRACT FROM AUTHOR]

Within the spectral function approach we study the direct production and decay via the dikaon (dimuon) channel of f-mesons in the interactions of 2.4 and 2.7GeVprotons with light and medium target nuclei. It is shown that theK+ K- ( µ+µ-) invariant-mass distribution consists of the two components which correspond to the f decay “outside” and “inside” the target nucleus. The first (narrow) component has the free f width, while the second (broad) component is distorted by the nuclear matter due to resonance-nucleon scattering and a possible in-medium modification of the kaons and ?-meson at finite baryon density. The relative strength of the “inside” and “outside” components is analyzed in different scenarios for the f width and momentum cut. It is demonstrated that the width of the resulting dimuon invariant-mass distribution on medium nuclei is larger than the free f width by a factor of about two if the total f in-medium width is used and the respective cutoff for the f three-momentum is applied, whereas the resulting dikaon invariant-mass distribution has an insignificant sensitivity to the f in-medium properties due to the strong absorption of the K- in the surrounding nuclear matter. On the other hand, because of the distortion of the K+ and K- on their way out the target nucleus mainly due to the hadronic kaon potentials, the latter distribution is broadened and shifted to higher invariant masses, which means that the measurement of such broadening would give additional evidence for the modification of the kaon and antikaon properties in the nuclear medium. [ABSTRACT FROM AUTHOR]

The production of non-ϕK+K− pairs by protons at 2.83 GeV kinetic energy on C, Cu, Ag, and Au targets has been investigated by using the COSY-ANKE magnetic spectrometer. The K− momentum dependence of the differential cross section has been measured for laboratory polar angles θK± ≤ 12∘ over the 0.2-0.9 GeV/c range. The comparison of the data with detailed model calculations indicates an attractive K−-nucleus potential of about −60 MeV at normal nuclear matter density at a mean momentum of 0.5 GeV/c. However, this approach has difficulty in reproducing the smallness of the observed cross sections at low-K− momenta. [ABSTRACT FROM AUTHOR]

Inclusive cross sections σA = Ed3α(X, P21)/d3p 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 nucléon. 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. The comparability of the measured cross-section ratios with those obtained in the inclusive electron scattering off nuclei suggests 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. [ABSTRACT FROM AUTHOR]