  In this paper, we study the one-loop effective potential of a derivative
four-fermion model. As a result, an exact bumblebee-like potential is
radiatively generated. Afterwards, we generalize our study for a finite
temperature case and explicitly demonstrate the possibility of phase
transitions allowing for the restoration of the Lorentz symmetry. We also
investigate the low-energy effective action, from which we obtain the usual
kinetic term and the corresponding bumblebee potential.
