A general framework for analyzing string propagation on the quotient of a manifold by a discrete group is presented.The conditions necessary for modular invariance and absence of tachyons are discussed. Models with four or fewer generations which correspond to the standard embedding of the spin connection in the gauge group are analyzed. We all discuss some generalizations which may lead to more phenomenologically promising models.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics