Nucleon-Nucleon Scattering Phase Parameters in Higher-Symmetry Models

Abstract

The one-pion-exchange (OPE) and two-pion-exchange (TPE) contributions arising from the $U(6,6)$ and chiral-dynamical models are used to obtain the corresponding nucleon-nucleon phase parameters for various energies in the elastic scattering range. It is shown that the $U(6,6)$ OPE phase parameters differ from the usual OPE results only for $s$ and $p$ waves. The chiral-dynamical model, on the other hand, gives rise to an additional TPE contribution that has a comparable range and is as large as the usual TPE values. For values of $L$ greater than 3, this additional TPE contribution tends to cancel the usual TPE values.