2006/05/26 by M. Schelke, Mia Schelke, Riccardo Catena +5
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Particle physics theoretical and experimental studies #astro-ph #hep-ph
paper · pdf · doi:10.1103/physrevd.74.083505
published as Phys.Rev. D74 (2006) 083505 · 19 pages, 15 figures, LaTex, uses revtex4
arxiv created 2006/05/26 · openalex publication_date 2006/10/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A host of dark energy models and nonstandard cosmologies predict an enhanced Hubble rate in the early Universe: perfectly viable models, which satisfy big bang nucleosynthesis (BBN), cosmic microwave background and general relativity tests, may nevertheless lead to enhancements of the Hubble rate up to many orders of magnitude. In this paper we show that strong bounds on the pre-BBN evolution of the Universe may be derived, under the assumption that dark matter is a thermal relic, by combining the dark matter relic density bound with constraints coming from the production of cosmic-ray antiprotons by dark matter annihilation in the Galaxy. The limits we derive apply to the Hubble rate around the temperature of dark matter decoupling. For dark matter masses lighter than 100 GeV, the bound on the Hubble rate enhancement ranges from a factor of a few to a factor of 30, depending on the actual cosmological model, while for a mass of 500 GeV the bound falls in the range 50--500. Uncertainties in the derivation of the bounds and situations where the bounds become looser are discussed. We finally discuss how these limits apply to some specific realizations of nonstandard cosmologies: a scalar-tensor gravity model, kination models and a Randall-Sundrum D-brane model.