Physics

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...

Abstract: I will naively analyze the Regge trajectory of the leading-twist operators in the critical O(N) model to leading order in 1/N. The anomalous dimensions of these operators develop simple poles in the spin J, preventing one from naively...

Abstract: I shall describe the recent theoretical advances in the description of turbulence in different media.

An important point is how different the meaning of renormalization in turbulence is from what we used to know in the field theory.

For...

Abstract: Based on https://arxiv.org/abs/2408.11139(Link is external) (Link opens in new window) . In pure Einstein gravity, the amplitude for an arbitrary number of positive helicity gravitons to scatter is zero at tree-level. If a single negative...