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The present review gives a survey of recent developments and applications of the NambuJona-Lasinio model with N f = 2 and N f = 3 quark flavors for the structure of baryons. The model is an effective chiral quark theory which incorporates the SU(N f ) L ⊗SU(N f ) R ⊗U(1) V approximate symmetry of Quantum chromodynamics. The approach describes the spontaneous chiral symmetry breaking and dynamical quark mass generation. Mesons appear as quarkantiquark excitations and baryons arise as non-topological solitons with three valence quarks and a polarized Dirac sea. For the evaluation of the baryon properties the present review concentrates on the non-linear Nambu-Jona-Lasinio model with quark and Goldstone degrees of freedom which is identical to the Chiral quark soliton model obtained from the instanton liquid model of the QCD vacuum. In this non-linear model, a wide variety of observables of baryons of the octet and decuplet is considered. These include, in particular, electromagnetic, axial, pseudoscalar and pion nucleon form factors and the related static properties like magnetic moments, radii and coupling constants of the nucleon as well as the mass splittings and electromagnetic form factors of hyperons. Predictions are given for the strange form factors, the scalar form factor and the tensor charge of the nucleon."Though this be madness, yet there is method in it."Shakespeare, Hamlet, II-2 --

The effects of meson loops in the vacuum sector of the Nambu-Jona-Lasinio model are calculated. Using the effective action formalism we take consistently all nextto-leading-order 1 Nc terms into account. This leads to a symmetry-conserving approach, in which all features of spontaneously broken chiral symmetry, such as the Goldstone theorem, the Goldberger-Treiman and the Gell-Mann-Oakes-Renner relations are preserved. Contributions to qq and F π are calculated, and are shown to be substantial, at the level of ∼ 30%, consistent with the 1 Nc expansion. The leading nonanalytic terms in the chiral expansion of qq , F π and m π have the same form as the one-loop results of chiral perturbation theory.

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