Fluctuations and defect-defect correlations in the ordering kinetics of the O(2) model

The theory of phase ordering kinetics for the O(2) model using the Gaussian auxiliary field approach is reexamined from two points of view. The effects of fluctuations about the ordering field are included and we organize the theory such that the auxiliary field correlation function is analytic in the short-scaled distance (x) expansion. These two points are connected and we find in the refined theory that the divergence at the origin in the defect-defect correlation function {tilde g}(x) obtained in the original theory is removed. Modifications to the order-parameter autocorrelation exponent {lambda} are computed. {copyright} {ital 1997} {ital The American Physical Society}