K + production in proton and deuteron induced reactions at subthreshold energies

Abstract

The production ofK+ mesons in proton-nucleus and deuteron-nucleus collisions is analyzed with respect to one-step nucleon-nucleon (NN → N ΛK+),Δ- nucleon (ΔN → N Λ K+) and two-step pion-nucleon (πN → K+Λ) production channels on the basis of experimental ground state momentum distributions and free on-shell production processes. Whereas forK+ production in proton-nucleus reactions the secondary channelπN clearly dominates at subthreshold energies, meson and nucleon induced channels are of similar magnitude in deuteron-nucleus reactions. Contrary to nucleus-nucleus collisions theΔ induced reaction channels are found to be of minor importance. The experimental differentiation of the underlying microscopic reaction channels appears possible via differential proton —K+ coincidence measurements as shown in detail by the microscopic simulations including proton rescattering.