Constraints on the SU(3) Electroweak Model

Abstract

We consider a recent proposal by Dimopoulos and Kaplan to embed the electroweak SU(2)_L X U(1)_Y into a larger group SU(3)_W X SU(2) X U(1) at a scale above a TeV. This idea is motivated by the prediction for the weak mixing angle sin^2 theta_W = 1/4, which naturally appears in these models so long as the gauge couplings of the high energy SU(2) and U(1) groups are moderately large. The extended gauge dynamics results in new effective operators that contribute to four-fermion interactions and Z pole observables. We calculate the corrections to these electroweak precision observables and carry out a global fit of the new physics to the data. For SU(2) and U(1) gauge couplings larger than 1, we find that the 95% C.L. lower bound on the matching (heavy gauge boson mass) scale is 11 TeV. We comment on the fine-tuning of the high energy gauge couplings needed to allow matching scales above our bounds. The remnants of SU(3)_W breaking include multi-TeV SU(2)_L doublets with electric charge (+-2,+-1). The lightest charged gauge boson is stable, leading to cosmological difficulties.

17 pages, LaTeX, 4 figures embedded, uses JHEP.cls

References in corpus (4)

• The Effective Lagrangian in the Randall-Sundrum Model and Electroweak Physics
• The Weak Mixing Angle from an SU(3) Symmetry at a TeV
• Unification of Weak and Hypercharge Interactions at the TeV Scale
• Electroweak Unification into a Five-Dimensional SU(3) at a TeV

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• The structure of electroweak corrections due to extended gauge symmetries
• Higgs boson mass limits in perturbative unification theories
• Strong-Electroweak Unification at About 4 TeV
• The Weak Mixing Angle From TeV Scale Quark-Lepton Unification
• An Exceptional Electroweak Model