Evading Lyth bound in models of quintessential inflation

Quintessential inflation refers to an attempt to unify inflation and late-time cosmic acceleration using a single scalar field. In this letter we consider two different classes of quintessential inflation, one of which is based upon a Lagrangian with non-canonical kinetic term k(2)(phi)partial derivative(mu)phi partial derivative(mu)phi and a steep exponential potential while the second class uses the concept of steep brane world inflation. We show that in both cases the Lyth bound can be evaded, despite the large tensor-to-scalar ratio of perturbations. The postinflationary dynamics is consistent with nucleosynthesis constraint in these cases. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.