A Three-Family Standard-like Orientifold Model: Yukawa Couplings and Hierarchy

TL;DR

This paper investigates the hierarchy of Yukawa couplings in a string-derived Standard-like model with intersecting D6-branes, calculating instanton contributions and exploring implications for fermion mass hierarchies.

Contribution

It presents a detailed analysis of Yukawa coupling hierarchies in a three-family string model using worldsheet instantons, linking string theory constructions to fermion mass patterns.

Findings

Calculated leading worldsheet instanton contributions to Yukawa couplings.

Analyzed implications of Yukawa hierarchy for fermion masses.

Connected Type IIA and M-theory compactifications in the model.

Abstract

We discuss the hierarchy of Yukawa couplings in a supersymmetric three family Standard-like string Model. The model is constructed by compactifying Type IIA string theory on a Z_2 x Z_2 orientifold in which the Standard Model matter fields arise from intersecting D6-branes. When lifted to M theory, the model amounts to compactification of M-theory on a G_2 manifold. While the actual fermion masses depend on the vacuum expectation values of the multiple Higgs fields in the model, we calculate the leading worldsheet instanton contributions to the Yukawa couplings and examine the implications of the Yukawa hierarchy.