Spinflation

TL;DR

This paper explores how angular momentum in brane inflation models, termed spinflation, can extend inflation duration and address energy constraints, with implications for cosmological perturbations.

Contribution

It introduces spinflation as a novel mechanism to enhance inflation duration in DBI brane models with angular momentum, and develops a framework for perturbation analysis.

Findings

Spinflation can provide additional e-foldings during inflation.

Angular momentum is rapidly damped by cosmological expansion.

A general perturbation theory framework for multi-field non-standard kinetic inflation is established.

Abstract

We study the cosmological implications of including angular motion in the DBI brane inflation scenario. The non-canonical kinetic terms of the Dirac-Born-Infeld action give an interesting alternative to slow roll inflation, and cycling branes can drive periods of accelerated expansion in the Universe. We present explicit numerical solutions demonstrating brane inflation in the Klebanov-Strassler throat. We find that demanding sufficient inflation takes place in the throat is in conflict with keeping the brane's total energy low enough so that local gravitational backreaction on the Calabi-Yau manifold can be safely ignored. We deduce that spinflation (brane inflation with angular momentum) can ease this tension by providing extra e-foldings at the start of inflation. Cosmological expansion rapidly damps the angular momentum causing an exit to a more conventional brane inflation scenario. Finally, we set up a general framework for cosmological perturbation theory in this scenario, where we have multi-field non-standard kinetic term inflation.