A Vacuum Phase Transition Solves $H_0$ Tension

TL;DR

This paper proposes a vacuum phase transition model that, motivated by quantum gravity, can resolve the Hubble constant tension and improve data fit without introducing extra parameters beyond the standard cosmological model.

Contribution

It introduces the Parker vacuum metamorphosis model, which removes the H_0 tension and fits cosmological data better than ΛCDM, with no additional parameters.

Findings

Removes the H_0 tension with Δχ²=-7.5

Improves fit to weak lensing and Lyman alpha data

No preferred scale dependence in gravitational lensing amplitude

Abstract

Taking the Planck cosmic microwave background data and the more direct Hubble constant measurement data as unaffected by systematic offsets, the values of the Hubble constant $H_0$ interpreted within the $\Lambda$CDM cosmological constant and cold dark matter cosmological model are in $\sim 3.3 \sigma$ tension. We show that the Parker vacuum metamorphosis model, physically motivated by quantum gravitational effects and with the same number of parameters as $\Lambda$CDM, can remove the $H_0$ tension, and can give an improved fit to data (up to $\Delta\chi^2=-7.5$). It also ameliorates tensions with weak lensing data and the high redshift Lyman alpha forest data. We separately consider a scale dependent scaling of the gravitational lensing amplitude, such as provided by modified gravity, neutrino mass, or cold dark energy, motivated by the somewhat different cosmological parameter estimates for low and high CMB multipoles. We find that no such scale dependence is preferred.