Gauge Coupling Unification without Supersymmetry

Abstract

We investigate the prospects to achieve unification of the gauge couplings in models without supersymmetry. We restrict our discussion to $SU(5),SO(10)$ and $E_6$ models that mimic the structure of the Standard Model as much as possible ("conservative models"). One possible reason for the non-unification of the standard model gauge couplings are threshold corrections which are necessary when the masses of the superheavy fields are not exactly degenerate. We calculate the threshold corrections in conservative models with a Grand Desert between the electroweak and the unification scale. We argue that only in conservative $E_6$ models the corrections can be sufficiently large to explain the mismatch and, at the same time, yield a long-enough proton lifetime. A second possible reason for the mismatch are particles at an intermediate scale. We therefore also study systematically the impact of additional light scalars, gauge bosons and fermions on the running of the gauge coupling. We argue that for each of these possibilities there is a viable scenario with just one intermediate scale.

arXiv comment33 pages, 11 figures

References in corpus (27)

• Predictive Neutrino Spectrum in Minimal $SO(10)$ Grand Unification
• String Theory and the Path to Unification: A Review of Recent Developments
• Vector-like leptons: Higgs decays and collider phenomenology
• Fermion Masses in SO(10) Models
• A non Supersymmetric SO(10) Grand Unified Model for All the Physics below $M_{GUT}$
• Intermediate mass scales in the non-supersymmetric SO(10) grand unification: a reappraisal
• Dark Matter and Gauge Coupling Unification in Non-supersymmetric SO(10) Grand Unified Models
• Yukawa sector in non-supersymmetric renormalizable SO(10)
• Renormalization constants and beta functions for the gauge couplings of the Standard Model to three-loop order
• On the vacuum of the minimal nonsupersymmetric SO(10) unification
• Threshold Effects in SO(10) Grandunified Models and Solar Neutrino Puzzle
• A Unified Framework for Symmetry Breaking in SO(10)
• Implications of LEP Results for SO(10) Grandunification with Two Intermediate Stages
• Unification versus proton decay in SU(5)
• PyR@TE 2: A Python tool for computing RGEs at two-loop
• Squeezing out predictions with leptogenesis from SO(10)
• Roadmap of left-right models based on GUTs
• The Higgs: so simple yet so unnatural
• Generation Symmetry and E_6 Unification
• Efficacious Additions to the Standard Model
• On the chirality of the SM and the fermion content of GUTs
• Visualizing gauge unification with high-scale thresholds
• Quest For Unification
• Surveying the SO(10) Model Landscape: The Left-Right Symmetric Case
• Dark Matter in $E_6$ Grand Unification
• GUTs and String-GUTs
• Gauge federation as an alternative to unification

Cited by in corpus (17)

• Unification, Proton Decay and Topological Defects in non-SUSY GUTs with Thresholds
• Leptogenesis and fermion mass fit in a renormalizable $SO(10)$ model
• Predictive power of grand unification from quantum gravity
• A Predictive $SO(10)$ Model
• Threshold effects in SO(10) models with one intermediate breaking scale
• Realizing unification in two different SO(10) models with one intermediate breaking scale
• Non-supersymmetric SO(10) models with Gauge and Yukawa coupling unification
• An asymptotically safe SU(5) GUT
• Road map through the desert: unification with vector-like fermions
• Threshold effects on prediction for proton decay in non-supersymmetric $E_6$ GUT with intermediate trinification symmetry
• Flavor physics in SU(5) GUT with scalar fields in the 45 representation
• Mass hierarchy from the flavor symmetry in supersymmetric multi-Higgs doublet model
• Proton Lifetime Upper Bound in Non-SUSY SU(5) GUT
• Road map through the desert with scalars
• Flavour anomalies and dark matter assisted unification in $SO(10)$ GUT
• Minimal dark matter in $SU(5)$ grand unification
• Yukawa coupling unification in non-supersymmetric SO(10) models with an intermediate scale