Closed String Tachyons and Semi-Classical Instabilities

TL;DR

This paper proposes that the decay of bulk closed string tachyons leads to the annihilation of spacetime via Witten's bubble of nothing, connecting perturbative tachyons with semi-classical instabilities across various string theory scenarios.

Contribution

It introduces a conjecture linking closed string tachyon decay endpoints to spacetime annihilation and explores dualities and puzzles in string theory through this lens.

Findings

Perturbative tachyons correspond to spacetime decay via bubble of nothing.

The conjecture applies to Scherk-Schwarz, Melvin backgrounds, and orbifolds.

It suggests a web of dualities involving non-supersymmetric string theories.

Abstract

We conjecture that the end point of bulk closed string tachyon decay at any non-zero coupling, is the annihilation of space time by Witten's bubble of nothing, resulting in a topological phase of the theory. In support of this we present a variety of situations in which there is a correspondence between the existence of perturbative tachyons in one regime and the semi-classical annihilation of space-time. Our discussion will include many recently investigated scenarios in string theory including Scherk-Schwarz compactifications, Melvin magnetic backgrounds, and noncompact orbifolds. We use this conjecture to investigate a possible web of dualities relating the eleven-dimensional Fabinger-Horava background with nonsupersymmetric string theories. Along the way we point out where our conjecture resolves some of the puzzles associated with bulk closed string tachyon condensation.