Scaling and vortex dynamics after the quench of a system with a continuous symmetry

We study the dynamics of a system with a nonconserved complex order parameter, following a deep quench. In contrast to the case when the order parameter has a discrete symmetry, we observe an effective value of the dynamical exponent at early times of {φ}=0.375±{}0.005. In this regime, finite-size scaling of the scattering function is observed. At later times, we observe a crossover to {φ}=0.5±{}0.02. Our results indicate that any renormalization of the kinetic coefficient must be small.