UTILITY OF GALILEAN SYMMETRY IN LIGHT-FRONT PERTURBATION-THEORY - A NONTRIVIAL EXAMPLE IN QCD

Investigations have revealed a very complex structure for the coeffici ent functions accompanying the divergences for individual time(x(+))-o rdered diagrams in light-front perturbation theory. No guidelines seem to be available to look for possible mistakes in the structure of the se coefficient functions emerging at the end of a long and tedious cal culation, in contrast to covariant held theory. Since, in light-front field theory, the transverse boost generator is a kinematical operator which acts just like the two-dimensional Galilean boost generator in nonrelativistic dynamics, it may provide some constraint on the result ing structures. In this work we investigate the utility of Galilean sy mmetry beyond tree level in the context of coupling constant renormali zation in light-front QCD using the two-component formalism. We show t hat for each x(+)-ordered diagram separately, the underlying transvers e boost symmetry fixes relative signs of terms in the coefficient func tions accompanying the diverging logarithms. We also summarize the res ults leading to coupling constant renormalization for the most general kinematics.