Generation of symmetry-breaking term and vacuum structure in the chiral SU(2)(X)SU(2) model

The effect of Yukawa coupling on the vacuum structure is taken into account and vacuum properties are analysed in the chiral SU(2)(X)SU(2) sigma model. Mass spectra are obtained and PCAC is discussed. It turns out that if the Yukawa coupling is strong enough ( mod g mod >or=gcrit), there exist both fermion pair and boson condensates and the vacuum energy is lower than that in the case of ordinary spontaneous breaking. It is shown that the linear symmetry-breaking term can be generated from the vacuum structure.