D-brane worlds and the cosmological constant

TL;DR

This paper investigates the cosmological constant on a D-brane within p-brane backgrounds, deriving the energy-momentum tensor and analyzing the properties of the resulting perfect fluid, including its energy density, pressure, and sound speed.

Contribution

It provides a detailed derivation of the cosmological constant and energy-momentum tensor for a D-brane in p-brane backgrounds, interpreting it as a perfect fluid with specific properties.

Findings

Negative pressure on the D-brane fluid

Real speed of sound despite negative pressure

Explicit form of the energy-momentum tensor

Abstract

The cosmological constant on a D-brane is analyzed. This D-brane is in the background produced by the p-brane solutions. The energy-momentum tensor in this model has been found and the form of the cosmological constant has been derived. This energy-momentum tensor is interpreted as an energy-momentum tensor for a perfect fluid on the D-brane. The energy density and the pressure for this fluid have been derived. As it turned out the pressure is negative but the speed of sound is real.