Left-right symmetry breaking in NJL approach

We study left-right symmetric models which contain only fermion and gauge boson fields and no elementary scalars. The Higgs bosons are generated dynamically through a set of gauge- and parity-invariant 4-fermion operators. It is shown that in a model with a composite bi-doublet and two triplet scalars there is no parity breaking at low energies, whereas in the model with two doublets instead of two triplets parity is broken automatically regardless of the choice of the parameters of the model. For phenomenologically allowed values of the right-handed scale a tumbling symmetry breaking mechanism is realized in which parity breaking at a high scale μR propagates down and eventually causes the electro-weak symmetry breaking at the scale μEW ∼ 100 GeV. The model exhibits a number of low and intermediate mass Higgs bosons with certain relations between their masses. In particular, the components of the SU(2)L Higgs doublet χL are pseudo-Goldstone bosons of an accidental (approximate) SU(4) symmetry of the Higgs potential and therefore are expected to be relatively light.