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.

Speaker:

Ippocratis Saltas

Speaker affiliation:

University of Nottingham

Date:

Thursday, May 1, 2014 - 13:00

Room:

Lecture Theatre C - bdg 46

Title:

Classical and quantum aspects of unimodular gravity

Abstract: