D-brane orbiting NS5-branes

TL;DR

This paper investigates conditions under which a D-brane can orbit NS5-branes without decaying, avoiding tachyonic instability and maintaining stability through specific energy and angular momentum configurations.

Contribution

It demonstrates that certain energy and angular momentum values allow a D-brane to orbit NS5-branes stably, preventing decay due to tachyonic modes, which is a novel finding.

Findings

D-brane can orbit NS5-branes at a stable distance

Tachyonic degrees of freedom can be suppressed in special cases

Stable orbits prevent the decay of the D-brane

Abstract

We study real time dynamics of a Dp-brane orbiting a stack of NS5-branes. It is generally known that a BPS D-brane moving in the vicinity of NS5-branes becomes unstable due to the presence of tachyonic degree of freedom induced on the D-brane. Indeed, the D-brane necessarily falls into the fivebranes due to gravitational attraction and eventually collapses into a pressureless fluid. Such a decay of the D-brane is known to be closely related to the rolling tachyon problem. In this paper we show that in special cases the decay of D-brane caused by gravitational attraction can be avoided. Namely for certain values of energy and angular momentum the D-brane orbits around the fivebranes, maintaining certain distance from the fivebranes all the time, and the process of tachyon condensation is suppressed. We show that the tachyonic degree of freedom induced on such a D-brane really disappears and the brane returns to a stable D-brane.