Diversity in the Tail of the Intersecting Brane Landscape

TL;DR

This paper develops techniques to systematically classify intersecting brane models on a specific orientifold, revealing the diversity and distribution of gauge groups and generations, including the prevalence of three-generation models.

Contribution

It introduces a comprehensive method for enumerating all intersecting brane configurations with specific gauge groups and constraints, enabling efficient exploration of the model landscape.

Findings

All solutions for the T^6/Z_2 x Z_2 orientifold are classified.

Distribution of quark generations shows no special suppression of three generations.

The model landscape has a long tail with diverse low-energy physics structures.

Abstract

Techniques are developed for exploring the complete space of intersecting brane models on an orientifold. The classification of all solutions for the widely-studied T^6/Z_2 x Z_2 orientifold is made possible by computing all combinations of branes with negative tadpole contributions. This provides the necessary information to systematically and efficiently identify all models in this class with specific characteristics. In particular, all ways in which a desired group G can be realized by a system of intersecting branes can be enumerated in polynomial time. We identify all distinct brane realizations of the gauge groups SU(3) x SU(2) and SU(3) x SU(2) x U(1) which can be embedded in any model which is compatible with the tadpole and SUSY constraints. We compute the distribution of the number of generations of "quarks" and find that 3 is neither suppressed nor particularly enhanced compared to other odd generation numbers. The overall distribution of models is found to have a long tail. Despite disproportionate suppression of models in the tail by K-theory constraints, the tail in the distribution contains much of the diversity of low-energy physics structure.