We study nonequilibrium dynamics of $SU(2)$ pure gauge theory starting from initial overpopulation, where intense classical gauge fields are characterized by a single momentum scale $Q_s$. Classical-statistical lattice simulations indicate a quick evolution towards an approximate scaling behavior with exponent $3/2$ at intermediate times. Remarkably, the value for the scaling exponent may be understood as arising from the leading $\mathcal{O}(g^2)$ contribution in the presence of a time-dependent background field. The phenomenon is associated to weak wave turbulence describing an energy cascade towards higher momenta. This particular aspect is very similar to what is observed for scalar theories, where an effective cubic interaction arises because of the presence of a time-dependent Bose condensate.

• Received 2 May 2012

DOI:https://doi.org/10.1103/PhysRevD.86.074006