Chiral Type II Orientifold Constructions as M Theory on G2 Holonomy Spaces

We summarize some recent progress in constructing four-dimensional supersymmetric chiral models from Type II orientifolds. We present the construction a supersymmetric Standard-like Model and a supersymmetric GUT model to illustrate the new features of this approach and its connection to M theory on compact, singular G₂ holonomy spaces. The Standard-like model presented is the first example of a three-family supersymmetric orientifold model with the Standard Model as part of the gauge structure. We also discuss the connection of how chiral fermions arise in this class of models with recent results of M theory compactified on G₂ holonomy spaces.