Fields Annihilation and Particles Creation in DBI inflation

TL;DR

This paper studies a DBI inflation model with brane annihilation, analyzing how branes collision and particle creation affect the curvature perturbation spectrum and spectral index, revealing a shift to blue spectrum on large scales.

Contribution

It introduces a novel DBI inflation scenario with brane annihilation and examines its impact on cosmological perturbations, highlighting spectral index modifications and oscillatory features.

Findings

Large-scale modes exhibit a blue spectral tilt after brane collision.

Small-scale power spectrum recovers standard DBI inflation form with oscillations.

Brane annihilation influences curvature perturbations significantly.

Abstract

We consider a model of DBI inflation where two stacks of mobile branes are moving ultra relativistically in a warped throat. The stack closer to the tip of the throat is annihilated with the background anti-branes while inflation proceeds by the second stack. The effects of branes annihilation and particles creation during DBI inflation on the curvature perturbations power spectrum and the scalar spectral index are studied. We show that for super-horizon scales, modes which are outside the sound horizon at the time of branes collision, the spectral index has a shift to blue spectrum compared to the standard DBI inflation. For small scales the power spectrum approaches to its background DBI inflation value with the decaying superimposed oscillatory modulations.