Modular invariance, misalignment and finiteness in non-supersymmetric strings

Abstract

In this article we show that finite perturbative corrections in non-supersymmetric strings can be understood via an interplay between modular invariance and misaligned supersymmetry. While modular invariance is known to be crucial in closed-string models, its presence and role for open strings is more subtle. Nevertheless, we argue that it leads to cancellations in physical quantities such as the one-loop cosmological constant and prevents them from diverging. In particular, we show that if the sector-averaged number of states does not grow exponentially, as predicted by misaligned supersymmetry, all exponential divergences in the one-loop cosmological constant cancel out as well. To account for the absence of power-law divergences, instead, we need to resort to the modular structure of the partition function. We finally comment on the presence of misaligned supersymmetry in the known 10-dimensional tachyon-free non-supersymmetric string theories.

36 pages + appendices, 4 figures; v2: minor edits + references added

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Cited by in corpus (4)

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• Tachyons and Misaligned Supersymmetry in Closed String Vacua
• Towards Classification of $\mathcal{N}=1$ and $\mathcal{N}=0$ Flipped $SU(5)$ Asymmetric ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$ Heterotic String Orbifolds
• Non-supersymmetric strings on AdS${}_3$: a world-sheet perspective