A novel treatment of the proton-proton Coulomb force in proton-deuteron Faddeev calculations

Abstract

\n We present resently introduced novel approach to include th e proton-proton (pp)\n Coulomb force into the momentum space three-nucleon (3N) Faddeev calculations.\n It is based on a standard formulation for short range forces and relies on a\n screening of the long-range Coul omb interaction. In order to avoid all\n uncertainties connected with an application of the partial wave expansion,\n unsuitable when working with long-range forces, we apply directly the\n 3-dimensional pp screened Coulomb t-matrix. That main new ingredient, the\n 3-dimensional screened pp Coulomb t-matrix, is obtained by a numerical sol ution\n of the 3-dimensional Lippmann-Schwinger (LS) equation. Using a simple dynamical\n model for the nuclear part of the interaction we demonstrate the feasibility of\n that approach. The physical elastic pd scattering amplitude has a well defined\n screening limit and does not require renormalisation. Well converged elastic pd\n cro ss sections are obtained at finite screening radii. Also the proton-deuteron\n (pd) breakup observables can be determ ined from the resulting on-shell 3N\n amplitudes increasing the screening radius. However, contrary to the pd e lastic\n scattering, the screening limit exists only after renormalisation of the pp\n t-matrices.\n