Dark Energy, the Swampland and the Equivalence Principle

Abstract

It has recently been argued that string theory does not admit de Sitter vacua. This would imply that the current accelerated expansion of the universe is not driven by a cosmological constant (or vacuum energy) but by other means such as a quintessential scalar field. Such a scalar field is in general expected to couple to at least some matter species, such as dark matter. Cosmological observations already constrain such dark matter couplings strongly. We argue that there are a number of interesting scenarios to be explored, such as coupling functions which possess a minimum at finite field values. In these theories, the effective gravitational coupling between dark matter particles grows with time and are consistent with observations of the anisotropies in the cosmic microwave background radiation and large scale structures. We argue that such couplings might also help to alleviate the tension between the swampland conjectures and the properties of the quintessential potential. Observational signatures of violations of the equivalence principle in the dark sector are expected in the non-linear regime on intermediate or small scales.

Version accepted for publication in Phys.Ref.D. References added, additional information regarding the attractor mechanism during inflation, cosmological parameter explicitly stated, typos corrected, clarifications throughout the text. 9 pages, 6 figures

References in corpus (8)

• Cosmology and the Fate of Dilatation Symmetry
• Tidal Tails Test the Equivalence Principle in the Dark Sector
• Disformal couplings and the dark sector of the universe
• Searching for dark matter - dark energy interactions: going beyond the conformal case
• Testing coupled dark energy models with their cosmological background evolution
• New interactions in the dark sector mediated by dark energy
• Dark energy beyond quintessence: Constraints from the swampland
• Probing the imprints of generalized interacting dark energy on the growth of perturbations

Cited by in corpus (9)

• Cosmology with the EFTofLSS and BOSS: dark energy constraints and a note on priors
• Interacting dark energy from the joint analysis of the power spectrum and bispectrum multipoles with the EFTofLSS
• Dark matter relic density from conformally or disformally coupled light scalars
• Reconstructing a non-linear interaction in the dark sector with cosmological observations
• The CIDER simulations: Nonlinear structure formation in the Constrained Interacting Dark Energy Scenario
• Constraints on Late Time Violations of the Equivalence Principle in the Dark Sector
• Exponential quintessence with momentum coupling to dark matter
• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme
• On the road to percent accuracy VI: the nonlinear power spectrum for interacting dark energy with baryonic feedback and massive neutrinos