BILOCAL EFFECTIVE THEORY WITH THE INSTANTANEOUS FUNNEL INTERACTION AND ITS RENORMALIZATION

The bound-state problem for the pion as a quarkonium with the funnel ( Coulomb-plus-linear) interaction is solved in a framework that combine s the bilocal approach to mesons with the covariant generalization of the instantaneous-potential model. The potential interaction leads to dynamical breaking of chiral symmetry. However, the Coulomb potential leads to ultraviolet divergences that must be subtracted. A careful ch oice of the renormalization prescription is needed in order to get the correct chiral limit. The mass, the lepton decay constant of the pion , as well as the pion decay width in two photons are calculated.