Aspects of thermal leptogenesis in braneworld cosmology

Abstract

The mechanism of thermal leptogenesis is investigated in the high-energy regime of braneworld cosmology. Within the simplest seesaw framework with hierarchical heavy Majorana neutrinos, we study the implications of the modified Friedmann equation on the realization of this mechanism. In contrast with the usual leptogenesis scenario of standard cosmology, where low-energy neutrino data favors a mildly strong washout regime, we find that leptogenesis in the braneworld regime is successfully realized in a weak washout regime. Furthermore, a quasi-degenerate light neutrino mass spectrum is found to be compatible with this scenario. For an initially vanishing heavy Majorana neutrino abundance, thermal leptogenesis in the brane requires the decaying heavy Majorana neutrino mass to be M1 > 10^10 GeV and the fundamental five-dimensional gravity scale 10^12 < M5 < 10^16 GeV, which corresponds to a transition from brane to standard cosmology at temperatures 10^8 < Tt < 10^14 GeV.Comment: 7 pages, 3 figures, a few comments and references added. Final version to appear in Phys. Rev.

Quintessential kination and thermal production of gravitinos and axinos

“…It would be probably interesting to check if we can obtain a simultaneous compatibility of these two constraints with additional bounds, arising e.g. from leptogenesis and neutrino masses [64,65] or the quintessino abundance [66]. Figure 9: Feynman rules used in the derivation of |M i j | 2 for the vertices withã.…”

TeV scale leptogenesis inB−Lmodel with alternative cosmologies

“…Therefore, H can be enhanced from 10 −12 to 10 These results have to be compared to standard leptogenesis scenario in the BC [25,26] where typically the M 5 scale has to be as large as 10 10 GeV. For our values of M 5 , one expects a low value for the transition temperature (around 10-100 MeV).…”

“…[25,26]. In these cosmological models, the H parameter is changed and it is expected that these modifications could make more efficient leptogenesis process dumping the washout processes.…”

Interacting dark energy with inhomogeneous equation of state

“…These problems are alternatively discussed using anthropic principles as well [12]. Several other models have been proposed to explain the cosmic accelerated expansion by introducing decaying vacuum energy [13,14], a cardassian term in the Friedmann-Robertson-Walker (FRW) equations [15], a generalized Chaplygin gas (GCG) [16] and a phantom energy (ω < −1) arising from the violation of energy conditions [17,18,19]. Another possibility is the 'geometric dark energy' based on the Ricci scalar R represented by ℜ = R/12H…”