Physics

Abstract: In recent years, there have been various activities trying to better understand the interplay between non-invertible global symmetries and boundary conditions in quantum field theories, with applications ranging from scattering of solitons...

Abstract: Based on https://arxiv.org/abs/2408.11139 . In this talk we'll explain how self-dual metrics (which correspond to spacetimes containing only positive helicity gravitons) can be written as a sum over connected "tree" diagrams, which are...

Abstract: Based on a recent paper with Juan and Yue-Zhou (https://arxiv.org/pdf/2409.14218). In this talk I will first review the no-boundary wavefunction in the context of inflation, and explain its natural generalization to the density matrix of a...

Abstract: I will talk about the scattering problem in general relativity, and present a construction of a scattering theory resolving the problem for the linearised Einstein equations in a double null gauge against a Schwarzschild background. This...

Abstract: First introduced in the 60s, positivity bounds for S-matrices have undergone a revival in the past few years, with systematic implementations that improve by the day. Among the recent results are sharp bounds on the EFTs of various gauge...

Abstract: A key challenge for computation is solving problems in high dimensions. Two classic proposals for tackling high dimensional problems are the Bethe approximation, or "belief propagation", and the quantum Fourier transform. Tensor networks...

Abstract: Axion dark matter thermalizes by gravitational self-interactions and forms a Bose-Einstein condensate.  It is shown that the rethermalization of the axion fluid during the initial collapse of large scale overdensities at cosmic dawn...