Dark matter relic density in Gauss-Bonnet braneworld cosmology

Meehan, Michael T., and Whittingham, Ian B. (2014) Dark matter relic density in Gauss-Bonnet braneworld cosmology. Journal of Cosmology and Astroparticle Physics, 2014 (12). 034. pp. 1-18.

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The relic density of symmetric and asymmetric dark matter in a Gauss-Bonnet (GB) modified Randall-Sundrum (RS) type II braneworld cosmology is investigated. The existing study of symmetric dark matter in a GB braneworld (Okada and Okada, 2009) found that the expansion rate was reduced compared to that in standard General Relativity (GR), thereby delaying particle freeze-out and resulting in relic abundances which are suppressed by up to O(10^−2). This is in direct contrast to the behaviour observed in RS braneworlds where the expansion rate is enhanced and the final relic abundance boosted. However, this finding that relic abundances are suppressed in a GB braneworld is based upon a highly contrived situation in which the GB era evolves directly into a standard GR era, rather than passing through a RS era as is the general situation. This collapse of the RS era requires equating the mass scale m(α) of the GB modification and the mass scale m(σ) of the brane tension. However, if the GB contribution is to be considered as the lowest order correction from string theory to the RS action, we would expect m(α) > m(σ). We investigate the effect upon the relic abundance of choosing more realistic values for the ratio Rm ≡ mα/mσ and find that the relic abundance can be either enhanced or suppressed by more than two orders of magnitude. However, suppression only occurs for a small range of parameter choices and, overwhelmingly, the predominant situation is that of enhancement as we recover the usual Randall-Sundrum type behaviour in the limit Rm >> 1. We use the latest observational bound Ω(DM)h^2 = 0.1187 ± 0.0017 to constrain the various model parameters and briefly discuss the implications for direct/indirect dark matter detection experiments as well as dark matter particle models.

Item ID: 36994
Item Type: Article (Research - C1)
ISSN: 1475-7516
Keywords: dark matter experiments, extra dimensions, dark energy theory
Date Deposited: 24 Mar 2015 03:08
FoR Codes: 02 PHYSICAL SCIENCES > 0201 Astronomical and Space Sciences > 020103 Cosmology and Extragalactic Astronomy @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 100%
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