Non-Gaussianity beyond slow roll in multi-field inflation

Byrnes C, Tasinato G. Non-Gaussianity beyond slow roll in multi-field inflation. JCAP. 2009;2009(08):016.We study the non-Gaussianity generated during multiple-field inflation. Weprovide an exact expression for the bispectrum parameter f_NL which is validbeyond the slow-roll regime, valid for certain classes of inflationary models.We then study a new, exact multi-field inflationary model considering a casewhere the bispectrum grows to observable values at the end of inflation. Weshow that in this case the trispectrum is also large and may even provide thedominant signal of non-Gaussianity