arXiv subjects
Publications and source records attributed to A. Chafik.
Brane inflation can provide a promissing framework for solving the fine-tuning problem in standard inflationary models. The aim of this paper is to illustrate the mechanism by which this can be achieved. By considering the supersymmetric two-stage inflation model it is shown that the initial fine-tuning of the coupling parameter can be considerably relaxed. SubPlanckian values of the inflaton during inflation can also be obtained.
In this paper we reconsider the supersymmetric hybrid inflation in the context of the braneworld scenario . The observational bounds are satisfied with an inflationary energy scale $μ\simeq 4\times 10^{-4}M_p$, without any fine-tuning of the coupling parameter, provided that the five-dimensional Planck scale is $M_5\stackrel{<}{\sim} 2\times 10^{-3}M_p$ . We have also obtained an upper bound on the the brane tension .
We propose a new realisation of hybrid inflation in supergravity where the inflaton field does not appear in the superpotential but contributes only through the Kahler potential. The scalar potential derived from an R-invariant superpotential has the same form as that of the Linde's original version. The correct magnitude of the density perturbations amplitude is found without any fine-tuning of the coupling parameter in the superpotential for an acceptable value of the fundamental energy scale of the theory. The eta-problem was also resolved in this model.