Regulator and gauge dependence of the Abelian gauge coupling in asymptotically safe quantum gravity

TL;DR

This paper investigates how gauge and regulator choices affect the predicted UV completion of the Abelian gauge sector in asymptotically safe quantum gravity, finding scenarios where this completion is robust and independent of unphysical parameters.

Contribution

It systematically analyzes the dependence of the UV completion of the Abelian gauge sector on gauge and regulator choices within asymptotically safe quantum gravity.

Findings

Existence of points of minimal sensitivity to gauge and regulator parameters.

Indications that UV completion is a robust physical feature.

Physical quantities can become independent of unphysical choices.

Abstract

Both General Relativity and the Standard Model of particle physics are not UV complete. General Relativity is perturbatively non-renormalizable, while the Standard Model features Landau poles, where couplings are predicted to diverge at finite energies, e.g., in the Abelian gauge sector. Asymptotically safe quantum gravity may resolve both of these issues at the same time. In this paper, we assess the systematic uncertainties associated with this scenario, in particular with the gravitationally induced UV-completion of the Abelian gauge sector. Specifically, we study the dependence of this qualitative feature, namely the existence of a UV-complete gauge sector, on unphysical choices like the gauge, and the regulator function. Intriguingly, in some scenarios, we find simultaneous points of minimal sensitivity relative to both the regulator and gauge parameters, which allow for a UV completion. This provides further indications that the simultaneous UV-completion of quantum gravity and matter via an asymptotically safe fixed point is a robust physical feature, and that physical quantities, like scaling exponents, can become independent of unphysical choices.