Mapping Poincaré gauge cosmology to Horndeski theory for emergent dark energy

Abstract

The ten-parameter, quadratic Poincaré gauge theory of gravity is a plausible alternative to general relativity. We show that the rich background cosmology of the gauge theory is described by a non-canonical bi-scalar-tensor theory in the Jordan frame: the `metrical analogue'. This provides a unified framework for future investigation by the broader community. For many parameter choices, the non-canonical term reduces to a Cuscuton field of the form $\sqrt{|X^{\varphi \varphi }|}$. The Einstein-Cartan-Kibble-Sciama theory maps to a pure quadratic Cuscuton, whereas the teleparallel theory maps to the Einstein-Hilbert Lagrangian. We apply the metrical analogue to novel unitary and power-counting-renormalisable cases of Poincaré gauge theory. These theories support the concordance $\Lambda$CDM background cosmology up to an optional, effective dark radiation component, we explain this behaviour in terms of a stalled Cuscuton. We also obtain two dark energy solutions from one of these cases: accelerated expansion from a negative bare cosmological constant whose magnitude is screened, and emergent dark energy to replace vanishing bare cosmological constant in $\Lambda$CDM.

11 pages, 2 figures. Results previously presented at DAMTP on 14/02/20. Added substantial introduction to Poincaré gauge theory and its perturbative renormalisability. Added various references. Incorporated supplemental material into main text (previously hosted on GitHub). Titular change. Results unaffected. Accepted for publication by Phys. Rev. D

References in corpus (18)

• Large Magellanic Cloud Cepheid Standards Provide a 1% Foundation for the Determination of the Hubble Constant and Stronger Evidence for Physics Beyond LambdaCDM
• The Effective Field Theory of Inflation
• Planck evidence for a closed Universe and a possible crisis for cosmology
• Horndeski theory and beyond: a review
• The Expansion of the Universe is Faster than Expected
• Cuscuton: A Causal Field Theory with an Infinite Speed of Sound
• Cuscuton Cosmology: Dark Energy meets Modified Gravity
• Cuscuton and low energy limit of Horava-Lifshitz gravity
• Torsion Cosmology and the Accelerating Universe
• Selected topics in scalar-tensor theories and beyond
• Inflation with a Negative Cosmological Constant
• Cosmic acceleration with a negative cosmological constant in higher dimensions
• Classical big-bounce cosmology: dynamical analysis of a homogeneous and irrotational Weyssenhoff fluid
• Cosmic homogeneity: a spectroscopic and model-independent measurement
• Prospects of detecting spacetime torsion
• Ghost and singularity free theories of gravity
• Non-zero torsion and late cosmology
• The Minkowski quantum vacuum does not gravitate