Low Energy Unimodular Gravity

The theory of Unimodular Gravity(UG) has been proposed as a possible way of relaxing the cosmological constant problem yielding the same classical predictions than General Relativity (GR). In this thesis we built the quantum formulation of the theory and show that the cosmological constant is still protected. 

As a second step, we explored the possible differences with GR at the quantum level. For that we analyze quantum
effects in the presence of matter. 

We computed the beta functions and proved that are non-physical and can’t be used for that matter. We also compute the UV divergent contributions to the S-matrix for UG and GR showing that, at the one loop level, there is no way to distinguish between both theories.