Confining potential based on local wave equations

The authors investigate the extent to which the recently proposed local relativistic wave equations can account for the nonperturbative part of the qanti q-interaction. The wave equations lead to linear trajectories and a strong singlet-triplet splitting that survives in the limit of massless quarks as required by chiral symmetry. The flavour dependence of slopes and intercepts is discussed and perturbative QCD contributions in ladder approximation are analyzed. The main features of the spectrum turn out to be stable with respect to these perturbative corrections. Recent data on the mass of etasub(c) indicate that the scheme overestimates the actual value of the singlet-triplet splitting in the canti c-system by a factor two. It is concluded that a local relativistic potential is unable to account for all nonperturbative effects - sizeable contributions on the level of mass terms are missing. (Auth.)