D-Flation

TL;DR

This paper investigates how quantum fluctuations of D-particles in string-inspired brane cosmology can modify inflationary dynamics, potentially leading to observable effects like an increased tensor-to-scalar ratio.

Contribution

It introduces mechanisms by which D-particle quantum fluctuations influence the inflationary potential and perturbation ratios in string cosmology models.

Findings

Quantum D-particle fluctuations can alter the inflationary potential.

Enhanced tensor-to-scalar ratio can arise from vector field condensates or graviton production.

Proposes new links between string theory effects and inflationary observables.

Abstract

In a recent paper we showed how Starobinsky-like inflation could emerge from dilaton dynamics in brane cosmology scenarios based on string theory, in which our universe is represented as a three-brane and the effective potential acquires a constant term from a density of effectively point-like non-perturbative defects on the brane: "D-particles". Here we explore how quantum fluctuations of the ensemble of D-particles during the inflationary period may modify the effective inflationary potential due to the dilaton. We then discuss two specific ways in which an enhanced ratio of tensor to scalar perturbations may arise: via either a condensate of vector fields with a Born-Infeld action that may be due to such recoil fluctuations, or graviton production in the D-particle vacuum.