Yukawa Textures in Horava-Witten M-Theory

TL;DR

This paper explores how M-theory can naturally generate quark mass hierarchies and CKM mixing without fine tuning, using specific geometric configurations of 5-branes and Calabi-Yau manifolds.

Contribution

It proposes a novel mechanism within M-theory for achieving realistic quark mass and mixing hierarchies through geometric configurations, avoiding fine tuning.

Findings

A phenomenological model matches all CKM and quark mass data.

5-branes clustering near the second orbifold plane is crucial.

An explicit three-generation model with specific Calabi-Yau geometry is constructed.

Abstract

Recent advances in 11 dimensional Horava-Witten M-theory based on non-standard embeddings with torus fibered Calabi-Yau manifolds have allowed the construction of three generation models with Wilson line breaking to the Standard Model gauge symmetry. Central to these constructions is the existence of a set of 5-branes in the bulk. We examine within this framework the general structure of the matter Yukawa couplings and show that M-theory offers an alternate possible way of achieving the CKM and quark mass hierarchies without introducing undue fine tuning or (as in conventional analysis) small parameters raised to high powers. A phenomenological example is presented in accord with all CKM and quark mass data requiring mainly that the 5-branes cluster near the second orbifold plane, and that the instanton charges of the physical orbifold plane vanish. An explicit example of a three generation model with vanishing physical plane instanton charges based on a torus fibered Calabi-Yau three fold with a del Pezzo base $dP_7$ and Wilson line breaking is constructed.