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New Nonsupersymmetric Tachyon-Free Strings

Zihni Kaan Baykara1, Houri-Christina Tarazi2,3, and Cumrun Vafa1

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Phys. Rev. Lett. 136, 061602 – Published 11 February, 2026

DOI: https://doi.org/10.1103/3c5v-yv16

Abstract

In four decades of string theory research, only a handful of nonsupersymmetric tachyon-free strings with only one neutral scalar at tree level were found. We construct new nonsupersymmetric tachyon-free string theories using asymmetric orbifolds that serve as the lower-dimensional counterparts to the O(16)×O(16) string in 4, 6, and 8 dimensions, each featuring only one neutral scalar at tree level, chiral matter and positive leading order potential. The 4D construction uses a quasicrystalline orbifold.

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Phys. Rev. Lett. 136, 061602– Published 11 February, 2026
  • Received 16 September 2024
  • Revised 9 December 2025
  • Accepted 6 January 2026
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