Type-I vacua from non-geometric Orbifolds

Abstract

Some examples of Type-I vacua related to non geometric orbifolds are shown. In particular, the open descendants of the diagonal $Z_3$ orbifold are compared with the geometric ones. Although not chiral, these models exhibit some interesting properties, like twisted sectors in the open-string spectra and the presence of ``quantized'' geometric moduli, a key ingredient to ensure their perturbative consistency and to explain the rank reduction of their Chan-Paton groups.

Contribution to the Proceedings of IX Marcel Grossman Meeting, Rome, ITALY, July 2-8, 2000