Seishi Enomoto, Kazunori Kohri, Tomohiro Matsuda
The early Universe may have oscillations, kinations (nonoscillatory evolution), topological defects, relativistic and non-relativistic particles at the same time. These components, which may have distinguishable scaling exponents, may decay modulated. In this paper we study generation of the curvature perturbations caused by the modulated decay in the multi-component Universe. For our analytic calculation we consider the instant-decay approximation. The non-Gaussianity parameter is separated into the model-dependent and independent contributions, where the sign of the model-independent contribution is determined by the scaling exponents. We also find that the component, whose scaling exponent is very close to the radiation, can generate significant non-Gaussianity, and its sign could be either positive or negative. We also consider partial decay, in which a fraction of the component decays modulated.
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http://arxiv.org/abs/1301.3787
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