Energy spectrum of the Dirac oscillator in the Coulomb field
  The spectrum of the Dirac oscillator perturbed by the Coulomb potential is considered. The Regge trajectories for its bound states are obtained with the method of $\hbar$-expansion. It is shown that the split of the degenerate energy levels of the Dirac oscillator in the Coulomb field is approximately linear in the coupling constant. 
D. A. Kulikov, R. S. Tutik