EXTENDED NJL MODEL FOR LIGHT AND HEAVY MESONS WITHOUT Q-(Q)OVER-BAR THRESHOLDS

We consider the NJL model as an effective quark theory to describe the interaction which is responsible for the quark flavor dynamics at int ermediate energies. In addition to the usual ultraviolet cut-off which is necessary since the model is nonrenormalizable, we also introduce an infrared cut-off which drops off the unknown confinement part of th e quark interaction, which is believed to be less important for the fl avor dynamics. The infrared cut-off eliminates all q-(q) over bar thre sholds, which plague the application of the usual NJL model beyond low -energy pion physics. We apply this two-cut-off prescription to the ex tended NJL model with chiral and heavy quark symmetries proposed recen tly by us. We find a satisfactorily description even of the heavy meso ns with spin/parity J(P) = (O+, 1(+)). Furthermore, the shape-paramete rs of the Isgur-Wise function are studied as a function of the residua l heavy meson mass.