Heavy Meson Production in Proton-Nucleus Reactions with Empirical Spectral Functions

We study the production of $K^+, \rho, \omega$ and $\phi$ mesons in $p + ^{12}C$ reactions on the basis of empirical spectral functions. The high momentum, high removal energy part of the spectral function is found to be negligible in all cases close to the absolute threshold. Furthermore, the two-step process ($pN \rightarrow \pi N N; \pi N \rightarrow N + K^+, \rho, \omega, \phi$) dominates the cross section at threshold energies in line with earlier calculations based on the folding model.Comment: 18 pages, LaTeX, plus 14 postscript figures, submitted to Z. Phys.

Subthreshold K + Production on Nuclei by π + Mesons

The inclusive K + mesons production in π + –nucleus reactions in the subthreshold energy regime is analyzed with respect to the one–step (π + n → K + Λ) and the two– step (π + n → ηp1, ηp2 → K + Λ) incoherent production processes on the basis of an appropriate folding model, which allows one to take into account the various forms of an internal nucleon momentum distribution as well as on – and off–shell propagation of the struck target nucleon. Contrary to proton–nucleus reactions primary reaction channel is found to be significant practically at all considered energies. Detailed predictions for the K + total and invariant differential cross sections from π + C 12 – and π + Pb 208 – collisions at subthreshold energies are provided.