  The inclusive K+ mesons production in proton-nucleus collisions in the near
threshold and subthreshold energy regimes is analyzed with respect to the
one-step (pN->K+YN, Y=Lambda,Sigma) and the two-step (pN->NNpi, NN2pi;
piN->K+Y) incoherent production processes on the basis of an appropriate new
folding model, which takes properly into account the struck target nucleon
removal energy and momentum distribution (nucleon spectral function), extracted
from recent quasielastic electron scattering experiments and from many-body
calculations with realistic models of the NN interaction. Comparison of the
model calculations of the K+ double differential cross sections for the
reaction p+C at 1.2, 1.5 and 2.5 GeV beam energies with the existing
experimental data from the SATURNE experiment is given, illustrating both the
relative role of the primary and secondary production channels at considered
incident energies and those features of the cross sections which are sensitive
to the high momentum and high removal energy part of the nucleon spectral
function that is governed by nucleon-nucleon short-range and tensor
correlations. In--medium modifications of the available for pion and hyperon
production invariant energies squared due to the respective optical potentials
are needed to account for the experimental data on K+ production in the energy
region under consideration.
