Shintaro Karasawa | Searcharxiv

arXiv2015

Hybrid chiral condensate in the external magnetic field

We study the phase diagram of the Nambu-Jona-Lasinio model in the external magnetic field within the mean-field approximation, taking into account the inhomogeneous chiral condensate. It is shown that there appears a new type of the chiral condensate, endowed with two features of real kink crystal and dual chiral density wave, in the magnetic field. We also show that there are first order phase transitions between different inhomogeneous phases in the presence of magnetic field.

nucl-th↗

arXiv2014

Nambu-Goldstone bosons and the Higgs mechanism without Lorentz invariance: Analysis based on constrained-system theory

First, we develop the counting rule for Nambu-Goldstone bosons to the system including two-time derivative terms. In this case, the type-II Nambu-Goldstone bosons may appear along with the massive Nambu-Goldstone ones. The number of the bosons is not reduced in contrast to the system without two-time derivative terms. We also investigate the reduction of the degrees of freedom from the perspective of the Dirac-Bergmann theory of constraints and reproduce the counting rule for Nambu-Goldstone bosons without Lorentz invariance. Then, we construct the generic Higgs model and study a Higgs phenomenon with these Nambu-Goldstone bosons on the basis of the Dirac-Bergmann theory. We show that the gauge fields in this system absorb all of the Nambu-Goldstone bosons such as the type-I, type-II and massive ones.

hep-th↗