Speaker
Description
"What can solve the cosmological constant problem?
We present a modern interpretation of the problem of radiative corrections to vacuum energy from the point of view of generalised symmetries; in particular global (-1)-form symmetries associated with continuous couplings. It is generally argued that quantum gravity does not admit global symmetries. We point out that general relativity with a cosmological constant term posesses two global (-1)-form symmetries: topologically gauging one yields Henneaux-Teitelboim unimodular gravity, while gauging both leads to local vacuum-energy sequester. While the latter is known to solve the problem of radiative corrections to vacuum energy, we propose a general diagnostic for determining whether a gravitational theory admits a cosmological constant problem.
We also discuss parallels with the strong CP problem—where topological susceptibility diagnoses the problem—and illuminate related examples in 2d.
This talk is based on ongoing work with Altay Etkin, Farbod Rassouli, and Antonio Padilla."