Enhanced primordial gravitational waves from a stiff post-inflationary era due to an oscillating inflaton

Understand

We investigate two classes of inflationary models, which lead to a stiff period after inflation that boosts the signal of primordial gravitational waves (GWs).

• In both families of models studied, we consider an oscillating scalar condensate, which when far away from the minimum it is overdamped by a warped kinetic term, a la $\alpha$-attractors.
• This leads to successful inflation.
• The oscillating condensate is in danger of becoming fragmented by resonant effects when non-linearities take over.