M-Theory Through the Looking Glass: Tachyon Condensation in the E_8 Heterotic String

TL;DR

This paper investigates tachyon condensation in heterotic string theory with E_8 gauge group, revealing a worldsheet super-Higgs effect and exploring gauge choices, with implications for spacetime decay processes.

Contribution

It introduces a novel analysis of tachyon condensation in heterotic string theory using worldsheet methods and alternative gauge choices, clarifying the super-Higgs mechanism on the worldsheet.

Findings

Tachyon condensation induces a worldsheet super-Higgs effect.

Alternative gauge choices reveal the dynamical nature of the worldsheet gravitino.

Logarithmic CFT plays a role in understanding tachyon dynamics.

Abstract

We study the spacetime decay to nothing in string theory and M-theory. First we recall a nonsupersymmetric version of heterotic M-theory, in which bubbles of nothing -- connecting the two E_8 boundaries by a throat -- are expected to be nucleated. We argue that the fate of this system should be addressed at weak string coupling, where the nonperturbative instanton instability is expected to turn into a perturbative tachyonic one. We identify the unique string theory that could describe this process: The heterotic model with one E_8 gauge group and a singlet tachyon. We then use worldsheet methods to study the tachyon condensation in the NSR formulation of this model, and show that it induces a worldsheet super-Higgs effect. The main theme of our analysis is the possibility of making meaningful alternative gauge choices for worldsheet supersymmetry, in place of the conventional superconformal gauge. We show in a version of unitary gauge how the worldsheet gravitino assimilates the goldstino and becomes dynamical. This picture clarifies recent results of Hellerman and Swanson. We also present analogs of R_\xi gauges, and note the importance of logarithmic CFT in the context of tachyon condensation.