Week 03.10.2022 – 09.10.2022

The fundamental theory of quantum gravity is expected to manifest itself at low energies via a series of higher-derivative corrections to Einstein’s theory. Holography and supersymmetry are of great help to characterize such corrections in controlled scenarios: through holography, quantum gravity in Anti de Sitter (AdS) space has a rigorous definition in terms of a conformal field theory (CFT), while supersymmetry makes it possible to compute exact observables and make quantitative predictions. In this context, we will illustrate how a CFT generating function known as the superconformal index provides a microscopic explanation of the entropy of five-dimensional supersymmetric black holes in AdS. We will show how this match goes beyond the leading Bekenstein-Hawking term and includes higher-derivative corrections.

The Schwinger model is one of the simplest gauge theories, yet it is only solvable in the massless case. In order to obtain numerical results, the Kogut-Susskind lattice approach with staggered fermions is regularly used. I will show that, contrary to what it was believed, the lattice mass and the continuum mass are actually not the same, but they are related by a mass shift. This can be understood by considering the (anomalous) chiral symmetry in the massless case, and has the advantage of greatly improving convergence of the numerics. I will comment on the charge-q Schwinger model as well as the multiflavor Schwinger model.

Whereas scattering amplitudes probe physics at the shortest distances, cosmology probes physics at the largest scales. Nevertheless, many concepts discovered in the study of scattering amplitudes have an analogue for cosmological observables. In this talk I will describe some aspects of this program which I have recently been investigating such as the double copy, scattering equations, and soft limits, and will discuss how these directions are interrelated.