The use of configuration interaction method for describing "fine"-splitting effects in the bound two-quark system

Abstract

The screened quasi-relativistic potential is used for describing spin-orbit splitting in $^{3}P_{J}$ waves in quark-antiquark system. The Fermi-Breit equation is solved numerically in configuration interaction approximation. This approximation takes the mixing of wave functions into account up to the fifth order and corrects substantially perturbative calculations. We research the Lorentz nature of potential. The good quantitative results for $b\overline{b}$ and $c\overline{c}$ quarkonia and the quite acceptable qualitative characteristics for unequal quark masses are obtained.