On the spectrum and dualities of non-supersymmetric CHL strings
The CHL string is the simplest example of a string compactification with reduced gauge group rank, whose gauge symmetry enhancements can be non-simply laced as well as have associated Kac-Moody algebras with level higher than 1. In this talk I’ll explain the problem of constructing the non-supersymmetric cousins of this theory and what are their properties. I’ll argue that there are four of them in total, up to T-duality, and discuss their T-duality groups and massless/tachyonic spectrum at symmetric loci in tree-level moduli space. For one of them I’ll argue that there is a particularly well behaved strong coupling dual given by a type IIB orientifold, which explains an observed Bose-Fermi degeneration in one of its subsectors as coming from mutually BPS branes in the dual. This feature sets it apart from the more well known 10D non-supersymmetric heterotic strings as a particularly well behaved non-supersymmetric theory.

