CHIRAL DYNAMICS AND HEAVY-QUARK SYMMETRY IN A SOLVABLE TOY FIELD-THEORETIC MODEL

We study a solvable QCD-like toy theory, a generalization of the Nambu-Jona-Lasinio model, which implements chiral symmetries of light quarks and heavy quark symmetry. The chiral symmetric and chiral broken phases can be dynamically tuned. This implies a parity-doubled heavy-light meson system, corresponding to a (0-, 1-) multiplet and a (0+, 1+) heavy spin multiplet. Consequently the mass difference of the two multiplets is given by a Goldberger-Treiman relation and g(A) is found to be small. The Isgur-Wise function xi(omega), the decay constant f(B), and other observables are studied.