Renormalizability of alternative theories of gravity: differences between power counting and entropy argument

TL;DR

This paper compares power counting and entropy-based arguments for the renormalizability of alternative gravity theories, providing counterexamples that challenge the entropy argument's validity.

Contribution

It presents explicit counterexamples in various alternative gravity theories, highlighting discrepancies between power counting and entropy-based renormalizability arguments.

Findings

Counterexamples in $f(R)$, $f( extbf{G})$, $f(T)$, and Horava-Lifshitz gravity challenge the entropy argument.

Inconsistencies found between power counting and entropy-based approaches.

Results suggest the need to reconsider assumptions behind the entropy argument.

Abstract

It is well known that General Relativity cannot be considered under the standard of a perturbatively renormalizable quantum field theory, but asymptotic safety is taken into account as a possibility for the formulation of gravity as a non-perturbative renormalizable theory. Recently, the entropy argument has however stepped into the discussion claiming for a "no-go" to the asymptotic safety argument. In this paper, we present simple counter-examples, considering alternative theories of gravity, to the entropy argument as further indications, among others, on the possible flows in the assumptions on which the latter is based on. We consider different theories, namely curvature based extensions of General Relativity as $f(R)$, $f(\mathcal{G})$, extensions of Teleparallel Gravity as $f(T)$, and Horava-Lifshitz gravity, working out the explicit spherically symmetric solutions in order to make a comparison between power counting and the entropy argument. Even in these cases, inconsistencies are found.