In the unitary gauge the unphysical degrees of freedom of spontaneously broken gauge theories are eliminated. The Feynman rules are simpler than in other gauges, but it is non-renormalizable by the rules of power counting. On the other hand, it is formally equal to the limit $\xi \to 0$ of the renormalizable R$_{ \xi}$-gauge. We consider perturbation theory to one-loop order in the R$_{ \xi}$-gauge and in the unitary gauge for the case of the two-dimensional abelian Higgs model. An apparent conflict between the unitary gauge and the limit $\xi \to 0$ of the R$_{ \xi}$-gauge is resolved, and it is demonstrated that results for physical quantities can be obtained in the unitary gauge.
Categories: hep-th