PHASE STRUCTURE OF THE LINEAR SIGMA MODEL WITH ELECTRIC NEUTRALITY CONSTRAINT
Main Article Content
Abstract
The phase structure of the linear sigma model with the electric neutrality is systematically studied by means of the Cornwall-Jackiw-Tomboulis effective potential. The latter quantity is calculated in the improved Hartree – Fock (IHF) approximation which preserves the Goldstone theorem and the thermodynamic consistency. It results that in the chiral limit, as function of T , the pion condensate undergoes a second order phase transition and, as function of μ, it undergoes a first order phase transition. In the physical world, where the chiral symmetry is explicitly broken, the chiral symmetry gets partial restoration as T ( or μ ) grows and the pion condensation is a first order phase transition occurring at μ = μc < μm , the pion mass in vacuum.
Article Details
Keywords
linear sigma model, chiral symmetry, pion condensation, electric neutrality
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