Chaotic inflation and unitarity problem

Abstract

We consider a general chaotic inflation model with non-canonical kinetic term, resulting in attractor solutions for the inflation of quadratic or other monomial type. In particular, the form of the kinetic term and the potential is fixed due to the requirement that the inflation model is a quadratic form in the large field values of the inflaton. We show that a large coupling in the non-canonical kinetic term allows for the slow-roll inflation with sub-Planckian field values of the inflaton; the successful predictions of the quadratic or other monomial type chaotic inflation in light of BICEP2 results are maintained in our model. We find that due to the large rescaling of the inflaton field in the vacuum, there is no unitarity problem below the Planck scale.