Week 05.05.2025 – 11.05.2025

Tree-level string theory extends Einstein gravity by an infinite set of massive higher spin particles. From a purely spacetime perspective (if we didn't know about the worldsheet picture) the consistency of string amplitudes would appear truly miraculous. This prompts the question: is string theory the unique framework for a higher spin extension of gravity? We investigate this question by bootstrap methods, focussing on maximal 10D supergravity. We parametrize theory space by the first few EFT coefficients and by the on-shell coupling of the lightest massive state, and impose on these data causality and positivity constraints. While Type II string theory lives strictly inside the allowed region, we uncover a novel extremal solution of the bootstrap problem, which appears to contain a single linear Regge trajectory. We repeat a similar analysis for supergluon scattering.

I will discuss work in preparation which relates two quantities in 4d N=2 supersymmetric theories: the superconformal index, which contains information about protected local operators, and the twisted index. I will show that under appropriate restrictions on the theory and the space of supersymmetric deformations, these quantities coincide. I will then discuss some implications for the physics of the theory and its holographic dual.

I will describe work on a universal relevant deformation that takes local unitary 3d N=4 superconformal field theories to topological quantum field theories. For example, I will describe how Abelian mirror symmetry is related to generalizations of level rank duality, and I will also discuss some more general statements and constraints that arise via t Hooft anomaly matching.