Chiral fermions in asymptotically safe quantum gravity

TL;DR

This paper investigates whether quantum gravity effects in the asymptotic safety scenario induce chiral symmetry breaking in fermions, finding that such breaking is avoided at the Planck scale across various models, indicating stability of the phase diagram.

Contribution

It demonstrates that gravity-induced chiral symmetry breaking does not occur at the Planck scale in asymptotically safe quantum gravity for NJL-type models, regardless of fermion flavor number.

Findings

Gravity-induced chiral symmetry breaking is avoided at the Planck scale.

The phase diagram remains topologically stable under gravitational interactions.

Results are consistent across different numbers of fermion flavors.

Abstract

We study the consistency of dynamical fermionic matter with the asymptotic safety scenario of quantum gravity using the functional renormalisation group. Since this scenario suggests strongly coupled quantum gravity in the UV, one expects gravity-induced fermion self-interactions at energies of the Planck-scale. These could lead to chiral symmetry breaking at very high energies and thus to large fermion masses in the IR. The present analysis which is based on the previous works \cite{Christiansen:2015rva, Meibohm:2015twa}, concludes that gravity-induced chiral symmetry breaking at the Planck scale is avoided for a general class of NJL-type models, regardless of the number of fermion flavours. This suggests that the phase diagram for these models is topologically stable under the influence of gravitational interactions.