Symmetry of Cosmological Observables, a Mirror World Dark Sector, and the Hubble Constant
Abstract
We find that a uniform scaling of the gravitational freefall rates and photonelectron scattering rate leaves most dimensionless cosmological observables nearly invariant. This result opens up a new approach to reconciling cosmic microwave background and largescale 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 freefall 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.
 Publication:

Physical Review Letters
 Pub Date:
 May 2022
 DOI:
 10.1103/PhysRevLett.128.201301
 arXiv:
 arXiv:2107.13000
 Bibcode:
 2022PhRvL.128t1301C
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 High Energy Physics  Phenomenology
 EPrint:
 5 pages + references, 2 figures