Yukawa Textures And Horava-Witten M-Theory

TL;DR

This paper explores how Horava-Witten M-theory can naturally generate Yukawa and CKM hierarchies without small parameters, by analyzing the matter Kahler metric structure in specific geometric configurations.

Contribution

It demonstrates that phenomenological hierarchies can arise from M-theory models with particular brane placements and instanton charge conditions, offering an alternative to traditional Yukawa texture models.

Findings

Hierarchies are achievable without ad hoc small parameters.

Brane placement near the distant orbifold plane is crucial.

Vanishing instanton charges on the physical plane are necessary.

Abstract

The general structure of the matter Kahler metric in the $\kappa^{2/3}$ expansion of Horava-Witten M-theory with nonstandard embeddings is examined. It is shown that phenomenological models based on this structure can lead to Yukawa and V$_{\rm CKM}$ hierarchies (consistent with all data) without introducing ad hoc small parameters if the 5-branes lie near the distant orbifold plane and the instanton charges of the physical plane vanish. M-theory thus offers an alternate way of describing these hierarchies, different from the conventional models of Yukawa textures.