Abstract

I’m going to talk about inflation in single-field models with non-canonical kinetic terms of the form X to power n, where X = 1/2 (dphi/dt)^2. These terms arise naturally in an EFT approach to modelling inflation, and can also be seen to arise from certain string theory embeddings, such as DBI inflation. We have been able to give a general formalism for finding solutions of the equations of motion corresponding to non-canonical inflation, which can be shown to be an attractor in phase space wherever it exists. However, not every Lagrangian with higher-derivative kinetic operators supports non-canonical inflation, and not every set of initial conditions in a suitable theory will give rise to an inflationary trajectory. We give some sufficient conditions required for a Lagrangian to support inflation in the non-canonical regime, and investigate the problem of fine-tuning. We find that non-canonical kinetic terms tend to reduce the severity of the fine-tuning problem in general. The talk is based on arXiv:0912.1857 and arXiv:1002.2639 with Paul Franche, Bret Underwood and Alisha Wissanji.