Subthreshold and near-threshold K +-meson photoproduction on nuclei

Abstract

The inclusive K+-meson production in photon-induced reactions in the near-threshold and subthreshold energy regimes is analyzed for the one-step (γN → K+Y, Y=Λ, Σ) incoherent production processes on the basis of an appropriate new folding model that takes properly into account the struck-target nucleonremoval energy and the internal momentum distribution (nucleon spectral function), extracted from recent quasielastic-electron-scattering experiments and from many-body calculations based on realistic models of NN interaction. Simple parametrizations of the total and differential cross sections for K+ production in photon-nucleon collisions are presented. A comparison of the model calculations of the K+ differential cross sections for γ12C interactions in the threshold region with existing experimental data is given, which displays the contributions to K+ production at considered incident energies from the use of the single-particle part, as well as high momentum and high removal energy part, of the nucleon spectral function. Detailed predictions for the K+ total and differential cross sections for γ2H, γ12C, and γ208Pb interactions at subthreshold and near-threshold energies are provided. The effect of the uncertainties in the elementary K+-production cross sections on the K+ yield is explored.