Perturbative gauge theory in a background
Seminar Room 1, Newton Institute
Motivated by the gluon condensate in QCD I study Abelian gauge theory in the presence of a constant (p=0) gluon background. The background adds an extra \sim \mu^2\delta^4(p) term to the free (Abelian) gluon propagator. I show how to evaluate dressed Green functions at tree level in the coupling \alpha, but summed to all orders in the parameter \mu characterizing the background field. Instead of a pole at p^2=m^2, the dressed quark propagator has a discontinuity that vanishes exponentially for large p^2. For vanishing quark mass I study a propagator solution which breaks chiral symmetry spontaneously.