Cosmological Solution from D-brane motion in NS5-Branes background

TL;DR

This paper investigates the dynamics of a D3-brane near NS5-branes, deriving cosmological solutions from its motion, and explores the implications for FRW cosmologies and tachyon-like matter.

Contribution

It presents a detailed analysis of D3-brane dynamics governed by Dirac-Born-Infeld action near NS5-branes, extending to cosmological models with novel scalar field restrictions.

Findings

Existence of a regime where DBI action dominates

Restrictions on scalar field rolling speed

Derivation of new FRW cosmologies related to tachyon matter

Abstract

We study dynamics of a D3-brane propagating in the vicinity of k coincident NS5 branes. We show that when $g_s$ is small, there exists a regime in which dynamics of the D-brane is governed by Dirac-Born-Infeld action while higher order derivative in the expansion can not be neglected. This leads to a restriction on how fast scalar field may roll. We analyze the motion of a rolling scalar field in this regime, and extend the analysis to cosmological systems obtained by coupling this type of field theory to four dimensinal gravity. It also leads to some FRW cosmologies, some of which are related to those obtained with tachyon matter.