Cosmological constant and gravitational theory on D-brane

TL;DR

This paper derives a modified gravitational equation on a curved D-brane, revealing how the cosmological constant depends on brane tension and charges, and linking matter presence to dark energy.

Contribution

It introduces a new effective gravitational theory on a D-brane that differs from Einstein's equations, highlighting the role of brane parameters in cosmological constant tuning.

Findings

The effective gravitational equation on the D-brane is significantly different from Einstein's.

The brane's cosmological constant depends on a balance between tension and charges.

Non-zero matter stress tensor correlates with a non-zero cosmological constant.

Abstract

In a toy model we derive the gravitational equation on a self-gravitating curved D-brane. The effective theory on the brane is drastically changed from the ordinal Einstein equation. The net cosmological constant on the brane depends on a tuning between the brane tension and the brane charges. Moreover, non-zero matter stress tensor exists if the net cosmological constant is not zero. This fact indicates a direct connection between matters on the brane and the dark energy.