Mass difference for charged quarks from asymptotically safe quantum gravity

TL;DR

This paper presents a quantum gravity-based model that predicts the mass difference between top and bottom quarks by analyzing fixed points in a microscopic theory, aligning with observed charge ratios.

Contribution

It introduces a first-principles approach linking quantum gravity fluctuations to quark mass differences and gauge couplings, providing a novel explanation within a consistent fixed-point framework.

Findings

Predicts the top-bottom quark mass difference from quantum gravity effects.

Derives a fixed-point value for the Abelian hypercharge consistent with observations.

Shows the charge ratio of bottom to top quark near the Standard Model value.

Abstract

We propose a scenario to retrodict the top and bottom mass and the Abelian gauge coupling from first principles in a microscopic model including quantum gravity. In our approximation, antiscreening quantum-gravity fluctuations induce an asymptotically safe fixed point for the Abelian hypercharge leading to a uniquely fixed infrared value that is observationally viable for a particular choice of microscopic gravitational parameters. The unequal quantum numbers of the top and bottom quark lead to different fixed-point values for the top and bottom Yukawa under the impact of gauge and gravity fluctuations. This results in a dynamically generated mass difference between the two quarks. To work quantitatively, the preferred ratio of electric charges of bottom and top in our approximation lies in close vicinity to the Standard-Model value of $Q_b/Q_t =-1/2$.