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TeV-scale GUTs

Keith R. Dienes, Emilian Dudas, Tony Gherghetta

TL;DR

The work investigates the possibility of grand unification at TeV energies by introducing extra spacetime dimensions, which induce power-law running of gauge couplings via Kaluza-Klein states. It shows that unification can be preserved at a scale around $M'_{\rm GUT}\sim 20$ TeV in favorable setups, while remaining perturbative and only mildly sensitive to unification-scale thresholds. Higher-loop power-law effects cancel due to the $N=2$ structure of KK towers, leaving primarily suppressed logarithmic corrections; threshold contributions can fine-tune agreement with experimental data. The approach opens avenues for collider-accessible GUT phenomenology, including potential signals from KK modes and novel connections to string theory, with broad implications for cosmology and model-building beyond the Standard Model.

Abstract

In this talk, we summarize our recent proposal for lowering the scale of grand unification to the TeV range though the appearance of extra spacetime dimensions. Particular emphasis is placed on the perturbativity and predictivity of our scenario, as well as its sensitivity to unification-scale effects. (Proceedings of invited talks given by KRD at PASCOS '98; by TG at the European Network Meeting ``From the Planck Scale to the Electroweak Scale''; and by KRD and TG at SUSY '98.)

TeV-scale GUTs

TL;DR

The work investigates the possibility of grand unification at TeV energies by introducing extra spacetime dimensions, which induce power-law running of gauge couplings via Kaluza-Klein states. It shows that unification can be preserved at a scale around TeV in favorable setups, while remaining perturbative and only mildly sensitive to unification-scale thresholds. Higher-loop power-law effects cancel due to the structure of KK towers, leaving primarily suppressed logarithmic corrections; threshold contributions can fine-tune agreement with experimental data. The approach opens avenues for collider-accessible GUT phenomenology, including potential signals from KK modes and novel connections to string theory, with broad implications for cosmology and model-building beyond the Standard Model.

Abstract

In this talk, we summarize our recent proposal for lowering the scale of grand unification to the TeV range though the appearance of extra spacetime dimensions. Particular emphasis is placed on the perturbativity and predictivity of our scenario, as well as its sensitivity to unification-scale effects. (Proceedings of invited talks given by KRD at PASCOS '98; by TG at the European Network Meeting ``From the Planck Scale to the Electroweak Scale''; and by KRD and TG at SUSY '98.)

Paper Structure

This paper contains 9 sections, 4 equations, 2 figures.

Table of Contents

  1. Introduction
  2. Gauge Coupling Unification in the Presence of Extra Dimensions
  3. Perturbativity, Higher-Loop Corrections, and Sensitivity to Unification-Scale Thresholds
  4. New Questions Posed by TeV-Scale GUTs
  5. Proton Decay
  6. Fermion Masses and Soft Masses
  7. Need for Supersymmetry?
  8. Embeddings into String Theory
  9. Next Directions

Figures (2)

  • Figure 1: Unification of gauge couplings at the new unification scale $M'_{\rm GUT}\approx 20$ TeV, assuming the appearance of a single extra spacetime dimension of radius $R^{-1}=1$ TeV.
  • Figure 2: Values of $N\alpha'_{\rm GUT}$ for different values of $(\delta,\eta)$, as a function of $\mu_0\equiv R^{-1}$. In all cases, the perturbativity constraint $N\alpha'_{\rm GUT}\ll 4\pi$ is easily satisfied.