The $$(1+1)$$
(
1
+
1
)
dimensional generalized model where vector and axial vector interaction get mixed up with different strength is considered. Imposing a chiral constraint, the model can be expressed in terms of chiral boson. Then the theoretical spectra of this model has been determined in both the Lagrangian and Hamiltonian formalism. It is found that the massless degrees of freedom disappears from the spectra and the photon acquires mass as well. Imposition of chiral constraint brings a disaster so far as Lorentz invariance is concerned. An attempt has been made here to show the physical Lorentz invariance explicitly using Poincaré algebra.