Non-supersymmetric Orientifolds of Gepner Models

TL;DR

This paper explores non-supersymmetric orientifold models based on Gepner models, identifying configurations that are tachyon-free and contain the standard model, with some spectra exhibiting partial or full supersymmetry despite breaking bulk supersymmetry.

Contribution

It demonstrates the existence of tachyon-free, chiral orientifold configurations containing the standard model in non-supersymmetric Gepner model frameworks, with insights into tadpole cancellation and supersymmetry breaking.

Findings

Found non-supersymmetric, tachyon-free chiral configurations with the standard model.

Tadpole cancellation with hidden sectors only in bulk supersymmetry cases.

Many non-supersymmetric spectra are partly or fully supersymmetric at the massless level.

Abstract

Starting from a previously collected set of tachyon-free closed strings, we search for N=2 minimal model orientifold spectra which contain the standard model and are free of tachyons and tadpoles at lowest order. For each class of tachyon-free closed strings -- bulk supersymmetry, automorphism invariants or Klein bottle projection -- we do indeed find non-supersymmetric and tachyon free chiral brane configurations that contain the standard model. However, a tadpole-cancelling hidden sector could only be found in the case of bulk supersymmetry. Although about half of the examples we have found make use of branes that break the bulk space-time supersymmetry, the resulting massless open string spectra are nevertheless supersymmetric in all cases. Dropping the requirement that the standard model be contained in the spectrum, we find chiral tachyon and tadpole-free solutions in all three cases, although in the case of bulk supersymmetry all massless spectra are supersymmetric. In the other two cases we find truly non-supersymmetric spectra, but a large fraction of them are nevertheless partly or fully supersymmetric at the massless level.