Static and spherically symmetric wormholes in metric-affine theories of gravity

TL;DR

This paper explores the possibility of stable, traversable wormholes in extended metric-affine gravity theories, demonstrating that geometric modifications alone can support such structures without exotic matter.

Contribution

It shows that stable wormholes can exist in various modified gravity models relying solely on geometric degrees of freedom, without exotic matter.

Findings

Stable wormholes are possible in $f(R)$, $f(T)$, and $f(Q)$ gravity models.

Geometric degrees of freedom can satisfy energy conditions for wormhole stability.

Constraints on these models support the existence of traversable wormholes without exotic matter.

Abstract

We consider static and spherically symmetric wormhole solutions in extended metric-affine theories of gravity supposing that stability and traversability of these objects can be achieved by means of the geometric degrees of freedom. In particular, we consider $f(R)$ metric, $f(T)$ teleparallel, and $f(Q)$ symmetric teleparallel models where curvature, torsion, and non-metricity rule entirely the background geometry without invoking any exotic energy-momentum tensor as matter field source. Starting from the flaring out and null energy conditions, we gather together a series of constraints which allow us to state that stable and traversable wormholes can be derived in a purely geometric approach resorting to modified gravity theories with more degrees of freedom than general relativity.