Instability of Tachyon Supertube in Type IIA Godel Spacetime

TL;DR

This paper investigates the stability of tachyon supertubes in a G"odel spacetime with closed timelike curves, revealing that despite their BPS nature, they exhibit instabilities due to spacetime causality violations.

Contribution

It demonstrates the existence of unstable tachyon supertube solutions in a G"odel spacetime, highlighting the impact of closed timelike curves on brane stability.

Findings

Tachyon supertubes can be constructed as BPS D2-branes in G"odel spacetime.

Fluctuation analysis reveals negative-energy modes indicating instability.

Instability arises despite the BPS nature due to spacetime causality violations.

Abstract

We study the tachyon supertube probes in a type IIA supergravity background which is a stringy-like G\"odel spacetime and contains closed timelike curve. In the case of small value of $f$, which is a parameter of the background, we use the Minahan-Zwiebach tachyon action to obtain a single regular tube solution and argue that the tube is a BPS D2-brane. However, we find that the fluctuation around the tube configuration has a negative-energy mode. This means that the tachyon supertube, despite being a BPS configuration, develops an instability in the pathological spacetime with closed timelike curve which violates the causality.