Weyl Invariance in the gravitational sector

June 9, 2016
11:30am to 1:30pm

IFT Seminar Room/Red Room

Specialist level
Mario Herrero Valea

IFT Seminar Room/Red Room


It is been known since long ago that field theories enjoying scale invariance have an improved behaviour in the Ultra- violet. Here we explore the consequences of this symmetry in the presence of dynamical gravitation, where it is described in terms of Weyl invariance, local rescalings of the metric and the fields involved in the lagrangian. After thoroughly introducing some techniques of common use in the field theory approach to Quantum Gravity, we address two main questions. First, we study the equivalence premise between the Einstein and Jordan frame in a theory we dub Conformal Dilaton Gravity, where we find that equivalence is broken in the presence of a Weyl anomaly. Although a regularization that solves this issue exists, it is not clear that it can be implemented in a consistent framework.

Later, we move our attention to Unimodular Gravity, where Weyl invariance appears as a way to relax the problem of the cosmological constant, which is here given in terms of an integration constant, its value determined solely by initial conditions. By constructing a gauge fixing and ghost sector, we quantize the theory and we compute its one loop effective action. Our results suggest that the protection of the cosmological constant is preserved by the quantization process provided no anomaly arises in the Weyl symmetry.