The Spinless Relativistic Yukawa Problem
  Noticing renewed or increasing interest in the possibility to describe semirelativistic bound states (of either spin-zero constituents or, upon confining oneself to spin-averaged features, constituents with nonzero spin) by means of the spinless Salpeter equation generalizing the Schr\"odinger equation towards incorporation of effects caused by relativistic kinematics, we revisit this problem for interactions between bound-state constituents of Yukawa shape, by recalling and applying several well-known tools enabling to constrain the resulting spectra. 
Wolfgang Lucha, Franz F. Sch\"oberl
hep-ph math-ph math.MP nucl-th quant-ph