2019/10/31 by Florian Niedermann, Martin S. Sloth · 1 citation
Physics and Astronomy · #astro-ph.CO #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.103.l041303
published as Phys. Rev. D 103, 041303 (2021) · 6 pages, 2 figures, 1 table, v4: corrected BOSS likelihood in MontePython, v5: matches version published in PRD Letters (selected as Editors' suggestion)
arxiv created 2021/02/22 · arxiv updated 2021/02/24
New measurements of the expansion rate of the Universe have plunged the standard model of cosmology into a severe crisis. In this letter, we propose a simple resolution to the problem that relies on a first order phase transition in a dark sector in the early Universe, before recombination. This will lead to a short phase of a New Early Dark Energy (NEDE) component and can explain the observations. We model the false vacuum decay of the NEDE scalar field as a sudden transition from a cosmological constant source to a decaying fluid with constant equation of state. The corresponding fluid perturbations are covariantly matched to the adiabatic fluctuations of a sub-dominant scalar field that triggers the phase transition. Fitting our model to measurements of the cosmic microwave background (CMB), baryonic acoustic oscillations (BAO, and supernovae (SNe) yields a significant improvement of the best-fit compared with the standard cosmological model without NEDE. We find the mean value of the present Hubble parameter in the NEDE model to be H0=71.4 ± 1.0 ~\textrmkm \textrms-1 \textrmMpc-1 (68 % C.L.).