Evading Lyth bound in models of quintessential inflation

Understand

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 $k^2(\phi)\partial^\mu \phi \partial_\mu \phi$ 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 post-inflationary dynamics is consistent with nucleosynthesis constraint in these cases.