Flavor structure and coupling selection rule from intersecting D-branes

TL;DR

This paper explores how intersecting D-brane models determine flavor structures and coupling rules, revealing that discrete abelian symmetries influence Yukawa couplings and that realistic fermion masses require extended models beyond minimal setups.

Contribution

It formulates a general coupling selection rule for intersecting D-branes and analyzes the resulting flavor structures, highlighting the limitations of minimal models and the potential of extended models.

Findings

Couplings are governed by discrete abelian symmetries.

Minimal models struggle to produce realistic Yukawa matrices.

Extended models can generate non-trivial mass matrices.

Abstract

We study flavor structure and the coupling selection rule in intersecting D-brane configurations. We formulate the selection rule for Yukawa couplings and its extensions to generic n-point couplings. We investigate the possible flavor structure, which can appear from intersecting D-brane configuration, and it is found that their couplings are determined by discrete abelian symmetry. Our studies on the flavor structure and the coupling selection rule show that the minimal matter content of the supersymmetric standard model would have difficulty to derive realistic Yukawa matrices from stringy 3-point couplings at the tree-level. However, extended models have a richer structure, leading to non-trivial mass matrices.