Spinflation with backreaction

TL;DR

This paper investigates brane inflation with backreaction effects in flux compactifications, solving nonlinear equations numerically to assess the robustness of DBI inflation against backreaction corrections.

Contribution

It provides a detailed numerical analysis of backreaction effects in brane inflation, deriving the full Kaehler modulus and two-field potential in a supergravity background.

Findings

DBI inflation solutions are robust against nonlinear backreaction corrections.

Hierarchies of scales differ from slow-roll models for valid perturbative expansion.

Exact Kaehler modulus functional form is computed across the entire background.

Abstract

We study brane inflation in flux compactifications at the nonlinear level, solving the D3-brane DBI-equations of motion including backreaction from the D3-D7 brane potential and from perturbations of the warp factor. We first numerically compute the exact functional form of the Kaehler modulus valid on the entire supergravity background and obtain a two-field potential along radial and harmonic directions. We find that a valid perturbative expansion on the entire supergravity background with the Kaehler modulus integrated out adiabatically in DBI inflation requires hierarchies of scales that determine compactification parameters different from those typical in slow-roll models. Our numerical results then show that the DBI inflationary solutions are quite robust against these nonlinear corrections.