Chiral symmetry breaking patterns in the UL(n) x UR(n) meson model

Chiral symmetry breaking patterns are investigated in the U-L(n) x U-R(n) meson model. It is shown that new classes of minima of the effective potential belonging to the center of the Lie algebra exist for arbitrary flavor number n. The true ground state of the system is searched nonperturbatively and although multiple local minima of the effective potential may exist, it is argued that in regions of the parameter space applicable for the strong interaction, strictly a U-L(n) x U-R(n) -> U-V(n) spontaneous symmetry breaking is possible. The reason behind this is the existence of a discrete subset of axial symmetries, which connects various U-V(n) symmetric vacua of the theory. The results are in agreement with the Vafa-Witten theorem of QCD, illustrating that it remains valid, even without gauge fields, for an effective model of the strong interaction. DOI: 10.1103/PhysRevD.87.056006