Construction of a Schroedinger operator for nucleon-nucleon scattering at medium energy

The Marchenko method is used to construct a Schroedinger operator which generates a given set of nucleon-nucleon experimental phase shifts. Three examples concerning np scattering are considered (1S0, 3P1, 1D2). In each case the Marchenko method is employed with some modification, the most important being the choice of a non-zero reference potential. The phase shifts which are obtained agree quite well with the input ones. A striking result is brought to light: If one considers a case where only real phase shifts are used as the input and a case where the full complex phase shifts are used, the two resulting Schroedinger operators are intrinsically different in nature. (orig.)