Wednesday, June 5, 2013

1306.0191 (Mingzhe Li)

Note on the production of scale-invariant entropy perturbation in the
Ekpyrotic universe
   [PDF]

Mingzhe Li
In the standard entropic mechanism adopted in the simple Ekpyrotic models to generate the nearly scale-invariant and Gaussian primordial perturbation, the entropy direction is tachyonically unstable. In this paper, we consider the stable production of the scale-invariant entropy perturbation in the Ekpyrotic universe via non-minimal couplings. In this model the non-minimally coupled massless scalar field serves as a spectator and is stabilized by the non-minimal couplings. It always corresponds to the entropy field during the contraction and with appropriate couplings can obtain a scale-invariant spectrum. This scenario requires additional mechanisms such as curvaton or modulated preheating to convert the entropy perturbation to the curvature perturbation after the bounce.
View original: http://arxiv.org/abs/1306.0191

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