Exploration of origin and breaking mechanism of pseudospin symmetry in relativistic point-coupling model with similarity renormalization group

The pseudospin symmetry (PSS) is an important physical concept in atomic nuclei. The relativistic point-coupling model is first used to explore the origin and breaking mechanism of PSS in real nuclei with 208Pb as an illustrated example. PSS observed in the single particle spectra of heavy nuclei is reproduced in the present calculation. The influences of the different point-coupling interactions on PSS are investigated, it is found that the four-fermion scalar and vector couplings play a dominate role at PSS. The quality of PSS depends on the competition of four-fermion scalar and vector couplings. Those the PSS is better for the weakly bound levels and the energy splittings are more sensitive to the interaction strengths for the deeply bound levels are well explained in terms of the derivative of sigma potential with r. In combination with the similarity renormalization group, the origin and breaking mechanism of PSS are clarified.