Microscopic analysis of K^+-nucleus elastic scattering based on K^+N phase shifts

We investigate $K^{+}$-nucleus elastic scattering at intermediate energies within a microscopic optical model approach. To this effect we use the current $K^{+}$-nucleon {\it (KN)} phase shifts from the Center for Nuclear Studies of the George Washington University as primary input. First, the {\it KN} phase shifts are used to generate Gel'fand-Levitan-Marchenko real and local inversion potentials. Secondly, these potentials are supplemented with a short range complex separable term in such a way that the corresponding unitary and non-unitary {\it KN} $S$ matrices are exactly reproduced. These {\it KN} potentials allow to calculate all needed on- and off-shell contributions of the $t$ matrix,the driving effective interaction in the full-folding $K^{+}$-nucleus optical model potentials reported here. Elastic scattering of positive kaons from $^{6}$Li, $^{12}$C, $^{28}$Si and $^{40}$Ca are studied at beam momenta in the range 400-1000 MeV/{$c$}, leading to a fair description of most differential and total cross section data. To complete the analysis the full-folding model, three kinds of simpler $t\rho$ calculations are considered and results discussed. We conclude that conventional medium effects, in conjunction with a proper representation of the basic {\it KN} interaction are essential for the description of $K^{+}$-nucleus phenomena.Comment: 11 pages, 1 table, 12 figures, submitted to PR

Toward a Spin- and Parity-Independent Nucleon-Nucleon Potential

A supersymmetric inversion method is applied to the singlet $^1S_0$ and $^1P_1$ neutron-proton elastic phase shifts. The resulting central potential has a one-pion-exchange (OPE) long-range behavior and a parity-independent short-range part; it fits inverted data well. Adding a regularized OPE tensor term also allows the reproduction of the triplet $^3P_0$, $^3P_1$ and $^3S_1$ phase shifts as well as of the deuteron binding energy. The potential is thus also spin-independent (except for the OPE part) and contains no spin-orbit term. These important simplifications of the neutron-proton interaction are shown to be possible only if the potential possesses Pauli forbidden bound states, as proposed in the Moscow nucleon-nucleon model.Comment: 9 pages, RevTeX, 5 ps figure