Spinflation

Abstract

We study the cosmological implications of including angular motion in the Dirac–Born–Infeldbrane inflation scenario. The non-canonical kinetic terms of the Dirac–Born–Infeld actiongive an interesting alternative to slow-roll inflation, and cycling branes can drive periods ofaccelerated expansion in the Universe. We present explicit numerical solutionsdemonstrating brane inflation in the Klebanov–Strassler throat. We find that demandingsufficient inflation takes place in the throat is in conflict with keeping the brane’s totalenergy low enough that local gravitational back-reaction on the Calabi–Yau manifold canbe safely ignored. We deduce that spinflation (brane inflation with angular momentum) canease this tension by providing extra e-foldings at the start of inflation. Cosmologicalexpansion rapidly damps the angular momentum causing an exit to a more conventionalbrane inflation scenario. Finally, we set up a general framework for cosmologicalperturbation theory in this scenario, where we have multi-field non-standard kinetic terminflation.