Relativistic Quark-Antiquark Bound State Problem with Spin-dependent   Interactions in Momentum Space
  The work described in this paper is the first step toward a relativistic three-quark bound-state calculation using a Hamiltonian consistent with the Wigner-Bargmann theorem and macroscopic locality. We give an explicit demonstration that we can solve the two-body problem in momentum space with spin-dependent interactions. The form of the potential is a combination of linear+Coulomb+spin-spin+% spin-orbit+tensor, which includes confinement and is of the general form consistent with rotation, space-reflection and time-reversal invariance. Comparison is made with previous calculations using an alternate technique and with the experimental meson mass spectrum. The results obtained suggest that the model is realistic enough to provide a two-body basis for the three quark baryon problem in which the Poincar\'{e} group representation is unitary and cluster separability is respected. 
H.-C. Jean, D. Robson and A. G. Williams