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arXiv · 2107.13000

Symmetry of Cosmological Observables, and a High Hubble Constant as an Indicator of a Mirror World Dark Sector

Francis-Yan Cyr-Racine·Fei Ge·Lloyd Knox
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Abstract

We find that a uniform scaling of the gravitational free-fall rates and photon-electron scattering rate leaves most dimensionless cosmological observables nearly invariant. This result opens up a new approach to reconciling cosmic microwave background and large-scale structure observations with high values of the Hubble constant $H_0$: Find a cosmological model in which the scaling transformation can be realized without violating any measurements of quantities not protected by the symmetry. A "mirror world" dark sector allows for effective scaling of the gravitational free-fall rates while respecting the measured mean photon density today. Further model building might bring consistency with the two constraints not yet satisfied: the inferred primordial abundances of deuterium and helium.

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Francis-Yan Cyr-Racine, Fei Ge, Lloyd Knox. 2021-07-27. Symmetry of Cosmological Observables, and a High Hubble Constant as an Indicator of a Mirror World Dark Sector. https://doi.org/10.1103/physrevlett.128.201301

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