EU employment governance revisited

RPA calculation of K+-nucleus cross sections with a density-dependent Dirac-Brueckner NN interaction

“…The point-like proton distribution of the 12 C nucleus required in the present analysis is that deduced, after the proton finite-size correction has been made, from the electron-scattering charge density of Sick and McCarthy [14] and we have chosen equal n and p-distributions. For the K + -nucleon amplitude in free space, we have used here the full Bonn boson exchange model [15] which is actually one of the more elaborate descriptions of the KN interaction. In nuclear matter, this amplitude has been modified in order to take into account the coupling of the σ and ω mesons, whose exchange provides the dominant part of the medium-range KN interaction, to the polarization of the Fermi and Dirac seas.…”

Dirac sea effects in K+ scattering from nuclei

“…In our calculation, we have used the same basic ingredients as in ref [5]: the K + -nucleus optical potential has been built by folding the density-dependent K + -nucleon t-matrix by the nuclear densities, these nuclear densities have been deduced from electron scattering experiments, and the KN amplitude has been calculated using the Bonn boson exchange model [6]. The K +nucleus total cross-section has been deduced from the forward K + -nucleus elastic scattering amplitude using the optical theorem.…”

“…Since the parameters of the KN interaction have been determined [6] in order to reproduce the KN data in free space, the polarization of the Dirac sea in free space has already been taken into account in the KN amplitude, at least in average. Therefore, in nuclear matter, this free-space polarization of the Dirac sea must be substracted from the in-medium one.…”