Initial systematic investigations of the landscape of low layer NAHE extensions

Abstract

The discovery that the number of physically consistent string vacua is on the order of 10 500 has prompted several statistical studies of string phenomenology. Contained here is one such study that focuses on the Weakly Coupled Free Fermionic Heterotic String (WCFFHS) formalism. Presented are systematic extensions of the well-known NAHE (Nanopoulos, Antoniadis, Hagelin, Ellis) set of basis vectors, which have been shown to produce phenomenologically realistic models. Statistics related to the number of U (1)'s, the specific gauge groups and their factors, non-Abelian singlets, and spacetime supersymmetries (ST SUSYs) are discussed for the full range of models produced.These findings are compared with prior results of other large-scale investigations. Statistical coupling between the gauge groups and the number of ST SUSYs is also discussed. In particular, for order-3 extensions there is a correlation between the appearance of exceptional groups and enhanced ST SUSY. Also discussed are some three-generation GUT models found among the data sets. These models are unique because they come from basis vectors which still have a geometric interpretation -there are no "rank-cuts" in these models.

Gauge Models in D Dimensions

“…One way to approach these problems is to systematically survey the valid input parameters. Such systematic surveys have been performed in four large spacetime dimensions, [46][47][48][49][50][51]. Further, by restricting the class of models under investigation we can make the problem more tractable while still providing insight into the structure and "texture" of the landscape.…”