Kinetic preheating after α-attractor inflation

Abstract

We study preheating via kinetic couplings after dilaton-axion α-attractor inflation. We focus on E-model α-attractor driven inflation where the inflaton is kinetically coupled to an ultralight axion. In this class of models, the kinetic coupling is related to the form of the potential, and once the amplitude of the scalar curvature spectrum as well as the tensor-to-scalar ratio are specified, the model has no free parameters. We find that the kinetic couplings can lead to extremely efficient tachyonic preheating, with stronger preheating occurring at parameter values corresponding to smaller values of the tensor-to-scalar ratio. Preheating becomes extremely efficient below r≲1.6×10−5.