Dark spinor models in gravitation and cosmology

TL;DR

This paper introduces a class of Lorentz-invariant dark spinor field theories coupled to gravity, exploring their cosmological solutions, stability, and potential to produce de Sitter-like expansion.

Contribution

It constructs a Lorentz-invariant non-local dark spinor theory, derives its energy-momentum tensor, and analyzes cosmological solutions including de Sitter states.

Findings

Existence of slow roll and fast roll de Sitter solutions

Construction of explicit energy-momentum tensor for dark spinors

Analysis of stability and perturbations in cosmological models

Abstract

We introduce and carefully define an entire class of field theories based on non-standard spinors. Their dominant interaction is via the gravitational field which makes them naturally dark; we refer to them as Dark Spinors. We provide a critical analysis of previous proposals for dark spinors noting that they violate Lorentz invariance. As a working assumption we restrict our analysis to non-standard spinors which preserve Lorentz invariance, whilst being non-local and explicitly construct such a theory. We construct the complete energy-momentum tensor and derive its components explicitly by assuming a specific projection operator. It is natural to next consider dark spinors in a cosmological setting. We find various interesting solutions where the spinor field leads to slow roll and fast roll de Sitter solutions. We also analyse models where the spinor is coupled conformally to gravity, and consider the perturbations and stability of the spinor.