Subthreshold K + meson production in proton–nucleus reactions and nucleon spectral function

Abstract

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.