## Modulaton

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Modulaton refers to a new mechanism for generating density perturbations from inflation, inhomogeneous or modulated reheating scenario, introduced in [1]. The tern "modulaton" was introduced in [2], where different scenario using modulaton is discussed. This field does not contribute significantly to the energy density, neither during inflation, like in multi-field inflation, or after inflation, like in the curvaton case.

In the modulated reheating scenario, spatial fluctuations in the decay rate of the inflaton field to ordinary matter lead to fluctuations in the reheating temperature. In many models of inflation the coupling of the inflaton to normal matter is determined by the vacuum expectation values of fields in the theory. If those fields are light during inflation (this is a generic situation in the minimal models of supersymmetric inflation) they will fluctuate leading to density perturbations through the proposed mechanism. These fluctuations could easily dominate over the ones generated through the standard mechanism. The new scenario has several consequences for inflation model building and observations. The proposed mechanism allows to generate the observed level of density perturbations with a much lower scale of inflation and thus generically predicts a smaller level of gravitational waves. The relation between the slope of the spectrum of the produced density perturbations and the potential of the inflaton field is different from the standard relations obtained in the context of slow roll inflation. Because the field responsible for the fluctuations is not the inflaton, it can have significantly larger self couplings and thus density perturbations could be non-Gaussian. The non-Gaussianity can be large enough to be detectable by CMB and Large Scale Structure observations.

References:
• [1]^ G. Dvali, A. Gruzinov and M. Zaldarriaga, Phys. Rev. D 69 (2004) 023505 [arXiv:astro-ph/0303591].
• [2]^ D. Langlois and L. Sorbo, Primordial perturbations and non-Gaussianities from modulated trapping,'' JCAP 0908 (2009) 014 [arXiv:0906.1813 [astro-ph.CO]]