Dilaton assisted two-field inflation from no-scale supergravity

Abstract

We present a two-field inflation model where inflaton field has a non-canonical kinetic term due to the presence of a dilaton field. It is a two-parameter generalization of one-parameter Brans-Dicke gravity in the Einstein frame. We show that in such an inflation model the quartic and quadratic inflaton potentials, which are otherwise ruled out by the present Planck-{\it Keck}/BICEP2 data, yield scalar spectral index and tensor-to-scalar ratio in accordance with the present data. Such a model yield tensor-to-scalar ratio of the order of $10^{-2}$ which is within the reach of $B-$mode experiments like {\it Keck}/BICEP3, CMBPol and thus can be put to test in the near future. This model yields negligible non-Gaussianity and no isocurvature perturbations upto slow-roll approximation. Finally, we show that such a model can be realised in the realm of no-scale supergravity.

Comments: 7 pages, 8 figures, Matches with the journal version to appear in Phys. Rev. D. Figures updated