Work

Combining pre- and post-recombination new physics to address cosmological tensions: Case study with varying electron mass and sign-switching cosmological constant

Year: 2024

Type: article

Abstract: It has recently been argued that the Hubble tension may call for a combination of both pre- and post-recombination new physics . Motivated by these considerations, we provide one of the first concrete case studies aimed at constructing such a viable combination. We consider models that have individually worked best on either end of recombination so far: a spatially uniform time-varying electron mass leading to earlier recombination (also adding non-zero spatial curvature), and a sign-switching cosmological constant inducing an AdS-to-dS transition within the Λ s CDM model. When confronted against Cosmic Microwave Background (CMB), Baryon Acoustic Oscillations , and Type Ia Supernovae data, we show that no combination of these ingredients can successfully solve the Hubble tension. We find that the matter density parameter Ω m plays a critical role, driving important physical scales in opposite directions: the AdS-to-dS transition requires a larger Ω m to maintain the CMB acoustic scale fixed, whereas the varying electron mass requires a smaller Ω m to maintain the redshift of matter-radiation equality fixed. Despite the overall failure, we use our results to draw general model-building lessons, highlighting the importance of assessing tension-solving directions in the parameter space of new physics parameters and how these correlate with shifts in other standard parameters, while underscoring the crucial role of Ω m in this sense.

Source: Physics of the Dark Universe

DOI: 10.1016/j.dark.2024.101676

Authors: Yo Toda, William Giarè, Emre Özülker, Eleonora Di Valentino, Sunny Vagnozzi

Institutions: Hokkaido University, University of Sheffield, Istanbul Technical University, University of Trento, Istituto Nazionale di Fisica Nucleare, Trento Institute for Fundamental Physics And Applications

Language: English

Topic: Cosmology and Gravitation Theories

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,240