Electroweak precision tests for asymptotic Grand Unification models

TL;DR

This paper investigates how asymptotic grand unification models, which predict new particles at TeV scales, affect electroweak precision tests and assesses the potential of future colliders to constrain these models.

Contribution

It provides the first analysis of electroweak precision constraints on asymptotic grand unification models with TeV-scale particles.

Findings

Current measurements are insensitive to these models.

Future colliders can significantly improve constraints, reaching up to 4 TeV.

Predicted Kaluza-Klein masses can be probed beyond LHC capabilities.

Abstract

Asymptotic grand unification is an alternative framework to traditional quantitative unification, as the renormalisation flow leads towards an ultra-violet safe fixed point. Phenomenologically, 5-dimensional realisations permit new particles with masses as low as the TeV scale, well below the usual unification scale. We explore the impact of such models on electroweak precision observables, focusing on a minimal SU(5) template for concreteness. We show that current measurements are not sensitive to this class of models. Future colliders, such as CEPC and FCC-ee, can push the 95% limit on the Kaluza-Klein mass up to 2 and 4 TeV, respectively, beyond the direct reach of the LHC programme.