Aspects of the Dark Dimension in Cosmology

Abstract

It was recently understood that if the swampland conjectures are confronted to experiment they naturally point to a solution of the cosmological hierarchy problem in which the smallness of the dark energy is ascribed to an internal (dark) dimension with characteristic length-scale in the micron range. It was later inferred that the universal coupling of the Standard Model fields to the massive spin-2 Kaluza-Klein (KK) excitations of the graviton in the dark dimension leads to a dark matter candidate. Since the partial decay widths of KK gravitons into the visible sector must be relatively small to accommodate experiment, the model is particularly challenging to probe. We show that the model can accommodate neutrino masses associated to right-handed neutrinos propagating in the bulk of the dark dimension with an additional constraint imposed by neutrino oscillation data. After that, we study the impact of the KK tower in cosmology. We show that the modulation of redshifted 21-cm lines driven by $\mathrm{KK}\to \gamma \gamma$ could be within the reach of next generation experiments (e.g. SKA and FARSIDE). We also show that indirect dark matter searches could uncover the $\mathrm{KK}\to \gamma \gamma$ signal. These two observations combined have the potential for model identification. Finally, we explore the global structure of the inflationary phase and demonstrate that the model parameters required for a successful uniform inflation driven by a 5-dimensional cosmological constant (corresponding to a flat region of the 5-dimensional potential) are natural.

Matching version accepted for publication in PRD

References in corpus (19)

• On the Geometry of the String Landscape and the Swampland
• Tests of the Gravitational Inverse-Square Law below the Dark-Energy Length Scale
• BICEP / Keck XIII: Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season
• Black Hole Bound on the Number of Species and Quantum Gravity at LHC
• General Constraints on Dark Matter Decay from the Cosmic Microwave Background
• Cosmological constraints on exotic injection of electromagnetic energy
• The Dark Dimension and the Swampland
• Constraining DM through 21 cm observations
• Constraining Neutrino Masses, the Cosmological Constant and BSM Physics from the Weak Gravity Conjecture
• Dark-Matter Decays and Self-Gravitating Halos
• Testing for Large Extra Dimensions with Neutrino Oscillations
• Neutrinos in Large Extra Dimensions and Short-Baseline ${\nu }_e$ Appearance
• Astrophysical Constraints from the SARAS3 non-detection of the Cosmic Dawn Sky-Averaged 21-cm Signal
• Large Extra Dimensions and neutrino experiments
• Do you smell something decaying? Updated linear constraints on decaying dark matter scenarios
• The Dark Dimension in a Warped Throat
• Swampland Constraints on Neutrino Masses
• The dark dimension, the Swampland, and the origin of cosmic rays beyond the GZK barrier
• The Effective Planck Mass and the Scale of Inflation

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• From infinite to infinitesimal: Using the Universe as a dataset to probe Casimir corrections to the vacuum energy from fields inhabiting the dark dimension
• Fuzzy Dark Matter and the Dark Dimension
• Large extra dimensions from higher-dimensional inflation
• Does the Cosmological Constant really indicate the existence of a Dark Dimension?
• Probing the Dark Dimension with Auger data
• A small Universe
• Bulk Black Hole Dark Matter
• Dark Dimension and the Effective Field Theory limit
• Bulk/boundary Modular Quintessence and DESI
• Signatures of Bulk Neutrinos in the Early Universe
• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme
• Primordial Power Spectrum of Five Dimensional Uniform Inflation
• Gravity-Matter Sum Rules in models with a single extra-dimension
• Confinement from Distance in Metric Space and its Relation to Cosmological Constant
• Dark Dimension Right-handed Neutrinos Confronted with Long-Baseline Oscillation Experiments
• A trial to understand the supersymmetry relations through extension of the second quantized fermion and boson fields, either to strings or to odd dimensional spaces
• Searching for a Dark Dimension Right-handed Neutrino in KATRIN
• Breaking Free from the Swampland of Impossible Universes through the DESI Portal
• The Cosmological Constant, Dark Matter and the ElectroWeak Scale meet in the Swampland