A Critique of the Asymptotic Safety Program

• Main Author: John F. Donoghue
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2020-03-01
• Series: Frontiers in Physics
• Subjects: asymptotic safety; quantum gravity; effective field thoery; quadratic gravity; Lorentzian
• Online Access: https://www.frontiersin.org/article/10.3389/fphy.2020.00056/full

The present practice of Asymptotic Safety in gravity is in conflict with explicit calculations in low energy quantum gravity. This raises the question of whether the present practice meets the Weinberg condition for Asymptotic Safety. I argue, with examples, that the running of Λ and G found in Asymptotic Safety are not realized in the real world, with reasons which are relatively simple to understand. A comparison/contrast with quadratic gravity is also given, which suggests a few obstacles that must be overcome before the Lorentzian version of the theory is well behaved. I make a suggestion on how a Lorentzian version of Asymptotic Safety could potentially solve these problems.