Primordial trispectrum from entropy perturbations in multifield DBI model

Abstract

We investigate the primordial trispectra of the generalmultifield DBI inflationary model. In contrast with the single fieldmodel, the entropic modes can source the curvature perturbations onthe super horizon scales, so we calculate the contributions from theinteraction of four entropic modes mediating one adiabatic mode tothe trispectra, at the large transfer limit (TRS >> 1). Weobtained the general form of the 4-point correlation functions,plotted the shape diagrams in two specific momenta configurations,``equilateral configuration'' and ``specialized configuration''. Ourfigures showed that we can easily distinguish the two differentmomenta configurations.