Investigation of relativistic symmetry from different fields with the similarity renormalization group

Abstract

Influences from different fields of mesons and photons on the relativistic symmetry are reinvestigated with the similarity renormalization group method (SRG). The energy splittings of pseudospin doublet and spin doublet are extracted from the SRG calculations. From the point view of the SRG method, $\omega$ field is revealed to exert great effect on the pseudsospin symmetry by nonrelativistic term, dynamical effect and spin–orbit interaction. Both nonrelativistic term and dynamical effect are also dominant in the influence of the $\sigma$ field on the pseudsospin symmetry. With the increasing strength of the photon field, the evolution of nonrelativistic component provides the main contribution to the increase of the total pseudospin energy splitting. The nonrelativistic term play the major role in influencing the isospin asymmetry in the pseudospin symmetry. As for the $\rho$ meson field, all three terms exert contrary influences on the pseudospin splitting between neutron doublet and proton doublet. The spin symmetry which is quasi-isospin symmetric is revealed to be due to the relativistic effect by spin–orbit term.