The Renormalization Group flow of unimodular f(R) gravity

TL;DR

This paper investigates the quantum properties of unimodular f(R) gravity within the asymptotic safety framework, revealing an interacting fixed point and compatibility with Standard Model matter, offering insights into the cosmological constant problem.

Contribution

It provides the first evidence of an interacting fixed point in unimodular f(R) gravity and explores its compatibility with Standard Model matter.

Findings

Evidence for an interacting fixed point in unimodular f(R) gravity

Compatibility of unimodular asymptotic safety with Standard Model matter

Potential implications for the cosmological constant problem

Abstract

Unimodular gravity is classically equivalent to General Relativity. This equivalence extends to actions which are functions of the curvature scalar. At the quantum level, the dynamics could differ. Most importantly, the cosmological constant is not a coupling in the unimodular action, providing a new vantage point from which to address the cosmological constant fine-tuning problem. Here, a quantum theory based on the asymptotic safety scenario is studied, and evidence for an interacting fixed point in unimodular f(R) gravity is found. We study the fixed point and its properties, and also discuss the compatibility of unimodular asymptotic safety with dynamical matter, finding evidence for its compatibility with the matter degrees of freedom of the Standard Model.