The Nambu--Jona-Lasinio (NJL) model is a model in which the hadron masses are generated by spontaneous symmetry breaking of the vacuum. In the modern form of the NJL model, we start with essentially massless quarks with zero range interactions between them, but with a cutoff in momentum space. Thus it is a low energy approximation to QCD in which form factor and other finite range effects have been ignored. The NJL model is only an effective theory, and it does not lead to quark confinement. However, it may work quite well in the region of interest in nuclear physics, i.e. for excitations less than the scalar meson mass.

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