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Advances in Astronomy
Volume 2010, Article ID 724525, 18 pages
http://dx.doi.org/10.1155/2010/724525
Review Article

Review of Local Non-Gaussianity from Multifield Inflation

1Fakultät für Physik, Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany
2Department of Physics, Pusan National University, Busan 609-735, Republic of Korea

Received 11 January 2010; Revised 5 May 2010; Accepted 9 June 2010

Academic Editor: Sarah Shandera

Copyright © 2010 Christian T. Byrnes and Ki-Young Choi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We review models which generate a large non-Gaussianity of the local form. We first briefly consider three models which generate the non-Gaussianity either at or after the end of inflation; the curvaton scenario, modulated (p)reheating, and an inhomogeneous end of inflation. We then focus on ways of generating the non-Gaussianity during inflation. We derive general conditions which a product or sum separable potential must satisfy in order to generate a large local bispectrum during slow-roll inflation. As an application, we consider two-field hybrid inflation. We then derive a formalism not based on slow roll which can be applied to models in which the slow-roll parameters become large before inflation ends. An exactly soluble two-field model is given in which this happens. Finally, we also consider further non-Gaussian observables, a scale dependence of and the trispectrum.