Do Incomplete GUT Multiplets Always Spoil Unification?

TL;DR

This paper investigates a new class of light vectorlike exotics with fractional electric charge that do not form complete GUT multiplets but still preserve gauge coupling unification, with implications for string theory and LHC phenomenology.

Contribution

It introduces a novel class of exotics compatible with GUT unification, arising naturally in heterotic string orbifold models, and explores their phenomenological implications.

Findings

Exotics can preserve gauge unification despite incomplete GUT multiplets.

These states naturally emerge from heterotic string orbifold constructions.

Potential signatures at the LHC are discussed.

Abstract

We consider a new class of light vectorlike exotics with fractional electric charge which do not come in complete representations of a grand unified gauge group, and are nevertheless compatible with gauge coupling unification and other predictions from Grand Unified Theories. Such states naturally arise in orbifold constructions of the heterotic string. Some aspects of their phenomenology and the consequences for the LHC are explored.