Inflation from D3-brane motion in the background of D5-branes

TL;DR

This paper explores a string theory-based inflation model where a D3-brane's motion near D5-branes drives cosmic inflation, with reheating occurring via tachyonic preheating after the radion field reaches the string scale.

Contribution

It introduces a novel inflation scenario involving D-brane dynamics with two scalar fields and demonstrates compatibility with observational data.

Findings

Inflation driven by radion field potential consistent with CMB constraints.

Reheating achieved through tachyonic preheating after radion reaches string length.

Dynamics transition from radion-driven inflation to tachyonic reheating.

Abstract

We study inflation arising from the motion of a BPS D3-brane in the background of a stack of k parallel D5-branes. There are two scalar fields in this set up-- (i) the radion field R, a real scalar field, and (ii) a complex tachyonic scalar field chi living on the world volume of the open string stretched between the D3 and D5 branes. We find that inflation is realized by the potential of the radion field, which satisfies observational constraints coming from the Cosmic Microwave Background. After the radion becomes of order the string length scale l_s, the dynamics is governed by the potential of the complex scalar field. Since this field has a standard kinematic term, reheating can be successfully realized by the mechanism of tachyonic preheating with spontaneous symmetry breaking.