Cosmology and two-body problem of D-branes

TL;DR

This paper explores the dynamics of D-branes in string theory, analyzing how their expansion behavior depends on their energy content and dimensionality, revealing conditions for accelerating and decelerating expansion.

Contribution

It provides a detailed analysis of the cosmological evolution of probe D-branes in background fields, highlighting the impact of gauge field energy density and brane dimension on expansion behavior.

Findings

Power-law expansion depends on brane dimension.

Decelerating expansion occurs when gauge field energy density is subdominant.

Accelerating expansion is possible for p ≤ 4 when gauge field dominates.

Abstract

In this paper, we investigate the dynamics and the evolution of the scale factor of a probe Dp-brane which move in the background of source Dp-branes. Action of the probe brane is described by the Born-Infeld action and the interaction with the background R-R field. When the probe brane moves away from the source branes, it expands by power law, whose index depends on the dimension of the brane. If the energy density of the gauge field on the brane is subdominant, the expansion is decelerating irrespective of the dimension of the brane. On the other hand, when the probe brane is a Nambu-Goto brane, the energy density of the gauge field can be dominant, in which case accelerating expansion occurs for $p \leq 4$. The accelerating expansion stops when the brane has expanded sufficiently so that the energy density of the gauge field become subdominant.