Duality without Supersymmetry: The Case of the SO(16)xSO(16) String

TL;DR

This paper extends string duality to non-supersymmetric theories, specifically establishing a duality between the tachyon-free $SO(16)\times SO(16)$ heterotic string and a related supersymmetric string, providing new insights into their stability and relationships.

Contribution

It constructs a duality between a non-supersymmetric, tachyon-free string and a supersymmetric string, the first such known duality in this context.

Findings

Perturbative massless states match within a certain interpolation range.

One-loop cosmological constants agree in both theories.

Presence of a soliton supports the duality conjecture.

Abstract

We extend strong/weak coupling duality to string theories without spacetime supersymmetry, and focus on the case of the unique ten-dimensional, nonsupersymmetric, tachyon-free $SO(16)\times SO(16)$ heterotic string. We construct a tachyon-free heterotic string model that interpolates smoothly between this string and the ten-dimensional supersymmetric $SO(32)$ heterotic string, and we construct a dual for this interpolating model. We find that the perturbative massless states of our dual theories precisely match within a certain range of the interpolation. Further evidence for this proposed duality comes from a calculation of the one-loop cosmological constant in both theories, as well as the presence of a soliton in the dual theory. This is therefore the first known duality relation between nonsupersymmetric tachyon-free string theories. Using this duality, we then investigate the perturbative and nonperturbative stability of the $SO(16)\times SO(16)$ string, and present a conjecture concerning its ultimate fate.