Non-Supersymmetric Type I Strings with Zero Vacuum Energy

TL;DR

This paper explores non-supersymmetric type I string models with zero vacuum energy, where supersymmetry is broken in the bulk but preserved on the brane, potentially enabling novel low-energy supersymmetry breaking scenarios.

Contribution

It introduces a class of non-supersymmetric type I models with zero vacuum energy that maintain supersymmetry on the brane and in the spectrum, offering new insights into string phenomenology.

Findings

Supersymmetry remains unbroken on the brane at all mass levels.

Bulk supersymmetry is broken but Fermi-Bose degeneracy is preserved in the spectrum.

Models suggest possible applications in low-energy supersymmetry breaking with large extra dimensions.

Abstract

We study open descendants of non-supersymmetric type IIB asymmetric (freely acting) orbifolds with zero cosmological constant. A generic feature of these models is that supersymmetry remains unbroken on the brane at all mass levels, while it is broken in the bulk in a way that preserves Fermi-Bose degeneracy in both the massless and massive (closed string) spectrum. This property remains valid in the heterotic dual of the type II model but only for the massless excitations. A possible application of these constructions concerns scenarios of low-energy supersymmetry breaking with large dimensions.