Dynamical Mass Generations and Collective Excitations in the (Supersymmetric-)Nambu$-$Jona-Lasinio Model and a Gauge Theory with Left-Right-Asymmetric Majorana Mass Terms

Abstract

The structure of effective potential surface of the Nambu$-$Jona-Lasinio (NJL) model with right-left asymmetric Majorana mass terms (corresponds to the single-flavor type-II seesaw situation of neutrino) is investigated. After the dynamical generation of Dirac mass, two collective modes appear similar to the case of ordinary NJL model, and the phase mode (phason), which corresponds to majoron or pion at vanishing Majorana mass parameter(s), has an excitation mass. The mechanism of generation of phason as a pseudo Nambu-Goldstone boson is examined by a mathematical manner, summarized into a theorem (claims as the generalized Nambu-Goldstone theorem). The mass of phason is also evaluated in a supersymmetric version of the NJL-type model, and phason mass takes the order of that of axion commonly accepted today. An $SU(2_{c})$-gauge model is constructed for the context of neutrino seesaw mechanism, and the Schwinger-Dyson equation of dynamical mass functions is examined. Several physical implications such as decay modes of phason, a non-linear sigma model for phason are given. It is proposed that the method/result of this paper can be applied to an understanding on the origin of the Kobayashi-Maskawa matrix.