Ippocratis Saltas
Speaker affiliation: 
University of Nottingham
Thursday, May 1, 2014 - 13:00
Lecture Theatre C - bdg 46
Classical and quantum aspects of unimodular gravity
Unimodular gravity, was originally suggested long time ago as a possible mechanism of explaining the cosmological constant problem. In the standard formulation of the theory, it is known that the unimodularity condition restricts the gauge symmetries of the gravitational action to a subset of the full diffeomorphisms, as well as that the classical dynamics of the theory are the same as those of standard General Relativity (GR). The quantum equivalence of the two theories, however, has not been well studied so far. In this talk, I will discuss the classical and quantum dynamics of unimodular gravity, based on a unimodular formulation of GR which enjoys full diffeomorphism symmetry by construction. I will first explain how the classical dynamics of the theory match exactly those of GR, and how the cosmological constant problem expresses itself in this context. I will proceed with presenting the key quantum properties of the theory in the context of the Exact Renormalisation Group, explaining how (in)equivalence with GR is established, and discussing some new features which emerge in this context.