Abstract
We perform a model-independent analysis of kinetically driven inflation (KDI) which (partially) includes Generalized G-inflation and Ghost inflation. We evaluate the background evolution splitting into the inflationary attractor and the perturbation around it. We also consider the quantum fluctuation of scalar mode with a usual scaling and derive the spectral index ignoring the contribution from the second order products of slow-roll parameters. Using these formalisms, we find that within our generic framework, the models of KDI which possess the shift symmetry of scalar field cannot create the quantum fluctuation consistent to the observation. Breaking the shift symmetry, we obtain a few essential conditions for viable models of KDI associated with the graceful exit.
Highlights
Inflation is an elegant scenario which can resolve the problems in the big bang universe by accelerating the early universe [1,2,3]
We have evaluated the cosmological background splitting into the inflationary attractor and the linear perturbations around it
Establishing the ansatz that all of the derivatives with respect to the scalar field are so small that they can be treated as the perturbations, we have derived the generic equation of motion for the linear perturbation of the scalar field
Summary
Inflation is an elegant scenario which can resolve the problems in the big bang universe by accelerating the early universe [1,2,3]. We do have another huge class of models accelerating the universe, so-called kinetically driven inflation (KDI) [17,18,19,20,21,22]. In this class, the kinetic terms of the scalar field play an. Using a wellknown approximation in which we keep the first-order slow-roll parameters only, we classify the asymptotic form of the mode function by the rank of the Hankel function Using those formalisms, we analyze the behavior of KDI for the shift symmetric case and φ-dependent case separately. In Appendix C, we shortly review a nonattractor solution, the so-called ultra slow-roll solution [30,31], which the theory can hold potentially
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
