Speaker: Joseph N. Ginocchio (T-16, LANL)

Relativistic pseudospin symmetry and the nucleon-nucleon interaction

Quasi - degenerate "pseudospin" doublets were discovered about thirty years ago in both spherical and deformed nuclei. Recently these pseudospin doublets were shown to arise from an SU(2) symmetry of the Dirac Hamiltonian which occurs when the scalar and vector potentials are opposite in sign but equal in magnitude. This symmetry occurs independent of the shape of the nucleus: spherical, axial deformed, triaxial, and gamma unstable. This pseudospin symmetry leads to conditions on the nuclear eigenfunctions. We survey the evidence that pseudospin symmetry is approximately conserved by testing the Dirac eigenfunctions of a Dirac Hamiltonian with realistic scalar and vector potentials. QCD sum rules in nuclear matter predict a scalar and vector potentials to be opposite in sign but approximately equal in magnitude which suggests a more fundamental rationale for pseudospin symmetry in terms of chiral symmetry. In order to determine if pseudospin symmetry is indeed a fundamental symmetry of nature, the nucleon-nucleon interaction is examined for pseudospin symmetry conservation.