We will have an exceptional seminar, of interest to both geometers and physicists, on Thursday 5th November, at 2pm in room O8.08. The speaker will be Kirill Krasnov, and his title is *A gauge theoretic formalism for gravity*. His abstract follows.

I will describe a formulation of 4-dimensional GR that uses connections instead of metrics. The metric appears as a derived object, and satisfies Einstein equations when the connection satisfies its field equations. There are some simplifications in this formalism, notably self-dual metrics are much easier to describe via connections than in the usual metric GR.

In 4 dimensions there exists an infinite-parametric family of “chiral” modified gravity theories. These are theories that propagate, as GR, just two polarisations of gravitons. They are simplest to describe using the above gauge-theoretic formulation of gravity. The Lagrangian is then just a general function of the curvature of the connection. This type of modifications of GR becomes important in regions with large Weyl curvature. I will describe how Kasner singularity of General Relativity gets resolved in modified gravity theories of this sort.