Norbert Schappacher (Strasbourg), Marie-Françoise Roy (Rennes)
Teresa Bautista (Max Planck Institute for Gravitational Physics, Golm)
The quantum effective action is a functional of the matter and gauge fields of a theory. It is a powerful object because the full quantum physics of the theory can be derived from it by doing simple classical manipulations. This action follows from integrating quantum fluctuations of the fields around their classical background, and in the case the fields are massless, the action becomes a nonlocal functional.
Despite being very powerful, nonlocal effective actions are very difficult to compute, specially on an arbitrary background metric. In this talk I will discuss a method to compute them for the case of Weyl-flat metrics and for theories that are classically Weyl invariant.
This method is based on the integration of Weyl anomalies, which are terms that appear in the quantum theory and spoil the classical Weyl invariance. In particular, I will focus on the beta function-type of Weyl anomalies, whose locality properties may be different, in general, from the measure- or conformal-type.