Phase structure of difermion condensates in the Nambu–Jona-Lasinio model: The size-dependent properties

We investigate finite-size effects on the phase structure of difermion condensates at finite temperature and density in the framework of the two-dimensional large-N limit Nambu–Jona-Lasinio model. We take into account size-dependent effects on the system by making use of zeta-function and compactification methods. The thermodynamic potential and the gap equation for the difermion condensed phase are then derived in the mean-field approximation. Size-dependent critical lines separating trivial and non-trivial difermion condensed phases are obtained imposing either periodic or anti-periodic boundary conditions on the spatial coordinate.