Non-supersymmetric branes and discrete topological terms

TL;DR

This paper investigates the role of discrete topological terms in non-supersymmetric heterotic string theories, analyzing NS5-branes and their worldvolume theories to understand their consistency and relation to spacetime topological features.

Contribution

It provides a consistency check of the NS5-brane spectrum via anomaly inflow and explores lower-dimensional gravitational theories with similar topological structures.

Findings

Confirmed the consistency of the proposed NS5-brane spectrum.

Identified the relation between worldvolume theories and spacetime topological terms.

Extended analysis to lower-dimensional gravitational models.

Abstract

In a recent work, Tachikawa and Zhang proved the existence of a discrete topological term in the unique non-supersymmetric heterotic string with no tachyons in ten dimensions. This theory features NS5-branes, whose chiral degrees of freedom are not well-understood due to the absence of dualities or supersymmetry. In this paper, we test the consistency of a tentative spectrum obtained by anomaly inflow, studying the relation between the worldvolume theory and the discrete topological term in spacetime. Furthermore, we conduct a bottom-up investigation of lower-dimensional gravitational theories with the same methods.