Diana Battefeld and Thorsten Battefeld JCAP05(2007)012 doi:10.1088/1475-7516/2007/05/012
Non-Gaussianities in N-flation
Diana Battefeld and Thorsten Battefeld
Show affiliationsWe compute non-Gaussianities in 
-flation, a string motivated model of assisted inflation with quadratic, separable potentials and masses given by the Marčenko–Pastur distribution. After estimating parameters characterizing the bispectrum and trispectrum in the horizon crossing approximation, we focus on the non-linearity parameter fNL, a measure of the bispectrum; we compute its magnitude for narrow and broad spreads of masses, including the evolution of modes after horizon crossing. We identify additional contributions due to the said evolution and show that they are suppressed as long as the fields are evolving slowly. This renders -flation indistinguishable from simple single-field models in this regime. Larger non-Gaussianities are expected to arise for fields that start to evolve faster, and we suggest an analytic technique for estimating their contribution. However, such fast roll during inflation is not expected in -flation, leaving (p)re-heating as the main additional candidate for generating non-Gaussianities.
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Issue 05 (May 2007)
Received 18 March 2007, accepted for publication 28 April 2007
Published 15 May 2007
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Non-Gaussianities in N-flation
Diana Battefeld and Thorsten Battefeld JCAP05(2007)012
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