Θ vacua states in heavy ion collisions in presence of dissipation and noise

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We have studied possible formation of Θ vacua states in heavy ion collisions. Random phases of the chiral fields were evolved in a finite temperature potential, incorporating the breaking of Uₐ(1) symmetry. Initial random phases very quickly settle into oscillation around the values dictated by the potential. The simulation study indicate that an initial Θ=0 state do not evolve into a Θ ≠ 0 state. However, an initial Θ ≠ 0 state, if formed in heavy ion collision, can survive, as a coherent superposition of a number of modes.