Multi-quark interactions with a globally stable vacuum

It is shown that U(3)L×U(3)R eight-quark interactions stabilize the asymmetric ground state of the well-known model with four-quark Nambu-Jona-Lasinio and six-quark 't Hooft interactions. The result remains when the reduced SU(3) flavour symmetry is explicitly broken by the general current quark mass term with mˆu≠mˆd≠mˆs.