Unification Scale, Proton Decay, And Manifolds Of G_2 Holonomy

TL;DR

This paper analyzes G_2 holonomy manifolds in particle physics models, focusing on threshold corrections, unification parameters, and proton decay modes, revealing potential enhancements in specific decay channels.

Contribution

It provides explicit calculations of threshold corrections in G_2 models and explores their implications for unification and proton decay, a novel analysis in this context.

Findings

Explicit threshold correction results for simple G_2 models

Estimated relations between GUT scale, Newton's constant, and alpha_GUT

Potential enhancement of p→π^0e^+_L decay mode

Abstract

Models of particle physics based on manifolds of $G_2$ holonomy are in most respects much more complicated than other string-derived models, but as we show here they do have one simplification: threshold corrections to grand unification are particularly simple. We compute these corrections, getting completely explicit results in some simple cases. We estimate the relation between Newton's constant, the GUT scale, and the value of $\alpha_{GUT}$, and explore the implications for proton decay. In the case of proton decay, there is an interesting mechanism which (relative to four-dimensional SUSY GUT's) enhances the gauge boson contribution to $p\to\pi^0e^+_L$ compared to other modes such as $p\to \pi^0e^+_R$ or $p\to \pi^+\bar\nu_R$. Because of numerical uncertainties, we do not know whether to intepret this as an enhancement of the $p\to \pi^0e^+_L$ mode or a suppression of the others.