TeV Scale Superstring and Extra Dimensions

TL;DR

This paper explores the possibility of unifying gauge and gravity couplings at TeV scales within string theory, considering extra large dimensions and analyzing proton decay constraints in Type I string models.

Contribution

It provides a detailed phenomenological analysis of TeV scale unification scenarios in Type I string theory with explicit model examples.

Findings

Proton decay bounds can be satisfied in Type I string models.

Different unification scenarios are explicitly illustrated.

Features of these scenarios are likely generic in other Type I strings.

Abstract

Utilizing the idea of extra large dimensions, it has been suggested that the gauge and gravity couplings unification can happen at a scale as low as 1 TeV. In this paper, we explore this phenomenological possibility within string theory. In particular, we discuss how the proton decay bound can be satisfied in Type I string theory. The string picture also suggests different scenarios of gauge and gravitational couplings unification. The various scenarios are explicitly illustrated with a specific 4-dimensional N=1 supersymmetric chiral Type I string model with Pati-Salam-like gauge symmetry. We point out certain features that should be generic in other Type I strings.