Abstract

I discuss the consequences of Lorentz violation on cosmology and in particular during slow-roll inflation. The model is a canonical scalar inflaton coupled to a fixed-norm timelike vector field, or “aether.” The vector is described by Einstein-aether theory, a vector-tensor theory of gravitational Lorentz violation. If the scale of Lorentz violation is sufficiently small compared to the Planck mass, and the strength of the scalar-aether coupling is suitably large, then the spin-0 and spin-1 perturbations grow exponentially and spoil the inflationary background. The effects of such a coupling on the CMB are too small to be visible to current or near-future CMB experiments; unusually, no isocurvature modes are produced at first order in a perturbative expansion around the aether norm. These results are discussed for both a general potential and a worked example, m^{2 \phi}2 inflation with a quadratic scalar-aether coupling term.