The kaon optical potential modified by Θ + Pentaquark excitation

We study the kaon nuclear optical potential including the effect of the Θ + pentaquark in a selfconsistent approach, starting from an extension of the Jülich meson-exchange potential as bare kaon-nucleon interaction. Significant differences between a fully self-consistent calculation and the low-density T ρ approximation are observed. Whereas the influence of the KN → Θ + absorption process is found to be negligible, due to the small Θ + KN coupling, the two-nucleon mechanism (KN N → Θ + N), estimated from the two-meson coupling of the pentaquark, provides the necessary additional kaon absorption to reconcile with data the systematically low theoretical K + −nucleus reaction cross sections.