Dynamical chiral symmetry breaking by a magnetic field in an effective multi-quark Lagrangian
Catalysis of dynamical symmetry breaking by a constant magnetic field in (3+1) dimensions is considered. We use the three flavour Nambu-Jona-Lasinio type model with 't Hooft and eight-quark interaction terms (the latter are crucial for the stability of the vacuum). It is shown that the multi-quark interactions introduce new additional features to this phenomenon: (a) the local minimum of the effective potential catalyzed by the constant magnetic field is smoothed out with increasing strength of the field at the characteristic scale H 1019G, (b) the multi-quark forces generate independently another local minimum associated with a larger dynamical fermion mass. This state may exist even for multi-quark interactions with a subcritical set of couplings, and is globally stable with respect to a further increase of the magnetic field.
1) A.A. Osipov, B. Hiller, A.H. Blin, J. da Providencia, e-Print: hep-ph/0701090, Phys. Lett. B (2007), in print.
2) A.A. Osipov, B. Hiller, A.H. Blin, J. da Providencia, e-Print: hep-ph/0607066, Annals of Physics (N.Y.) (2007), in print.