From de Sitter to de Sitter: decaying vacuum models as a possible solution to the main cosmological problems

TL;DR

Decaying vacuum models that evolve between two de Sitter phases can address multiple cosmological issues, including the singularity, horizon, inflation exit, baryogenesis, and the coincidence problem, potentially reducing the severity of the cosmological constant problem.

Contribution

This work demonstrates that running vacuum cosmologies transitioning between de Sitter phases can alleviate key cosmological problems and suggests a first-principles approach to the cosmological constant.

Findings

Decaying vacuum models can solve or mitigate the singularity and horizon problems.

These models provide a framework to address the graceful exit from inflation.

The approach offers a way to lessen the cosmological constant problem.

Abstract

Decaying vacuum cosmological models evolving smoothly between two extreme (very early and late time) de Sitter phases are capable to solve or at least to alleviate some cosmological puzzles, among them: (i) the singularity, (ii) horizon, (iii) graceful-exit from inflation, and (iv) the baryogenesis problem. Our basic aim here is to discuss how the coincidence problem based on a large class of running vacuum cosmologies evolving from de Sitter to de Sitter can also be mollified. It is also argued that even the cosmological constant problem become less severe provided that the characteristic scales of the two limiting de Sitter manifolds are predicted from first principles.