Second order gluon polarization for SU(N) theory in linear covariant gauge

Understand

The gluon polarization functional is evaluated for a generic linear covariant gauge and for any space dimension in pure Yang-Mills SU(N) theory up to second order in a generalized perturbation theory, where the zeroth order action is freely chosen and can be determined by some variational method.

• Some numerical data are given for the gluon propagator in Landau gauge and compared with Feynmann gauge.
• A comparison is given for several variational methods that can be set up by the knowledge of the second-order polarization.