Quantum quenches and thermalization via symmetry restoration

We study non-equilibrium dynamics of isolated quantum system via global quench. We consider a theory of 2-dimensional massless fermions with quartic interaction ( Gross- Neveu model ). The discrete $Z2$ symmetry, which is dynamically broken through generation of mass of the fermions, is restored during the zero temperature quench. This can be understood as an effective thermalization. The scaling of symmetry restoration time with the quench rate can be identified with the Kibble-Zurek scaling in the problem.