Disoriented chiral condensate in presence of dissipation and noise

We have investigated the phase transition and disoriented chiral condensate domain formation in linear sigma model. Solving the Langevin equation for the linear $\sigma$ model, we have shown that for zero mass pions the fields undergo phase transition above a certain temperature ($T_c$). For finite mass pions, there is no phase transition. It was also shown that when the fields, thermalised at temperature above $T_c$ are cooled down sufficiently rapidly, disoriented chiral condensate domains are formed quite late in the evolution, if the pions are assumed to be mass less. For massive pions, no large DCC domain is formed.