title: Non-gaussianity consistency relation for multifield inflation.
abstract: While detection of the "local form" bispectrum of primordial perturbations would rule out all single-field inflation models, multifield models would still be allowed. We show that multifield models described by the δN formalism obey an inequality between fNL and one of the local-form trispectrum amplitudes, τNL, such that τNL >1/2(6/5fN)(2) with a possible logarithmic scale dependence, provided that 2-loop terms are small. Detection of a violation of this inequality would rule out most of multifield models, challenging inflation as a mechanism for generating the primoridal perturbations.
authors.affiliation: Astronomical Institute, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan. sugiyama@astr.tohoku.ac.jp
authors.forename: Naonori Suma
authors.initials: NS
authors.lastname: Sugiyama
authors.forename: Eiichiro
authors.initials: E
authors.lastname: Komatsu
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Futamase