Subthreshold K[sup –]-Meson Production in Proton–Nucleus Reactions Revisited.

The inclusive K[sup –]-meson production in proton—nucleus collisions in the subthreshold energy regime is studied in the framework of an appropriate spectral function approach for incoherent primary proton—nucleon and secondary pion—nucleon production processes, which takes properly into account the nuclear mean-field potential effects on these processes as well as the final state interaction (FSI) among the outgoing nucleons participating in the one-step antikaon creation process. A detailed comparison of the model calculations of the K[sup –] differential cross sections is given for the reactions p + [sup 9]Be, p + [sup 63]Cu, and p + [sup 197]Au at subthreshold energies with the currently available experimental data obtained recently at the ITEP proton synchrotron and at SIS/GSI. It is found that the calculations with inclusion of the influence of both the nuclear density-dependent mean-field potentials and the elementary NN-FSI effects on the K[sup –] production from direct mechanism are able to reproduce, contrary to previous estimates based on the use only of the density-dependent mean fields in calculating the K[sup –] yield from this mechanism, the energy dependences of the invariant differential cross sections for “hard” antikaon creation in p[sup 9]Be and p[sup 63]Cu collisions. It is further shown that the NN-FSI effects play a minor role in describing the data on the spectrum of relatively soft K[sup –] mesons from p[sup 197]Au interactions at incident energy of 2.5 GeV. It is also shown that the relative strength of the proton- and pion-induced reaction channels in the subthreshold energy regime is governed by the kinematics of the experiment under consideration. The influence of the nucleon, kaon, and antikaon mean-field potentials on the K[sup –] yield is explored. It is demonstrated that, in line with previous findings, the K[sup –] optical potential has a strong... [ABSTRACT FROM AUTHOR]