Observable traces of non-metricity: new constraints on metric-affine gravity

TL;DR

This paper demonstrates that non-metricity in metric-affine gravity can produce observable effects in quantum fields, allowing constraints on non-metricity scale to be significantly improved using collider data.

Contribution

It provides the first experimental constraints on non-metricity effects in quantum fields within a broad class of metric-affine gravity theories.

Findings

Non-metricity induces 4-fermion contact interactions.

The non-metricity scale is constrained to be greater than 1 TeV.

The constraints improve previous bounds by several orders of magnitude.

Abstract

Relaxing the Riemannian condition to incorporate geometric quantities such as torsion and non-metricity may allow to explore new physics associated with defects in a hypothetical space-time microstructure. Here we show that non-metricity produces observable effects in quantum fields in the form of 4-fermion contact interactions, thereby allowing us to constrain the scale of non-metricity to be greater than 1 TeV by using results on Bhabha scattering. Our analysis is carried out in the framework of a wide class of theories of gravity in the metric-affine approach. The bound obtained represents an improvement of several orders of magnitude to previous experimental constraints.