Würzburg Seminar on Quantum Field Theory and Gravity

Motivated to understand the structure of the Hilbert spaces of gravitational theories, we consider one of their universal sectors: that of the "large gauge" modes, which live on (asymptotic) boundaries. I will discuss two examples. The first are the so-called boundary gravitons in AdS3. Leveraging their holographic relation to the T-Tbar deformation, we can extract the symmetries and (non)-locality properties of gravity beyond asymptotically AdS. As a second example, I will consider the IR sector of gauge theories in flat space, where one can construct a generating function for S-matrix elements which is invariant under certain asymptotic symmetries. I will show that this invariance is nothing but the associated soft theorem.