Electroweak Precision Constraints on Vector-like Fermions

Abstract

We calculate the oblique electroweak corrections and confront with the experiments in an extension of the Standard Model. The new fields added are a vector-like weak doublet and a singlet fermion. After electroweak symmetry breaking there is a mixing between the components of the new fields, but no mixing allowed with the standard fermions. Four electroweak parameters, $\hat{S}$, $\hat{T}$, W, Y are presented in the formalism of Barbieri et al., these are the generalization of the Peskin-Takeuchi S, T, U's. The vector-like extension is slightly constrained, $\hat{T}$ requires the new neutral fermion masses not to be very far from each other, allowing higher mass difference for higher masses and smaller mixing. $\hat{S},W,Y$ gives practically no constraints on the masses. This extension can give a positive contribution to $\hat{T}$, allowing a heavy Higgs boson in electroweak precision tests of the Standard Model.

11 pages, 3 figures, references added,sign correction, conclusion about heavy Higgs has changed

References in corpus (20)

• Big-Bang nucleosynthesis (Particle Data Group mini-review)
• The Cosmological Parameters 2006
• Bounds on Universal Extra Dimensions
• Minimal Dark Matter
• Improved Naturalness with a Heavy Higgs: An Alternative Road to LHC Physics
• The Minimal Moose for a Little Higgs
• Electroweak symmetry breaking after LEP1 and LEP2
• Effects of new leptons in Electroweak Precision Data
• Electroweak Symmetry Breaking via Top Condensation Seesaw
• The Minimal Set of Electroweak Precision Parameters
• Beyond S, T and U
• One-loop Radiative Corrections to the rho Parameter in the Littlest Higgs Model
• The Minimal Model for Dark Matter and Unification
• Dark matter and Higgs boson physics
• LHC and Dark Matter Signals of Improved Naturalness
• Using jet mass to discover vector quarks at the LHC
• R_b and New Physics: A Comprehensive Analysis
• Supersymmetry and precision data after LEP2
• Fermion Condensate Model of Electroweak Interactions
• Gap Equations and Electroweak Symmetry Breaking

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• Common origin of radiative neutrino mass, dark matter and leptogenesis in scotogenic Georgi-Machacek model
• A new feasible dark matter region in the singlet scalar scotogenic model
• The Muon Magnetic Moment and Physics Beyond the Standard Model
• The Two Scales of New Physics in Higgs Couplings
• Electroweak baryogenesis in the MSSM with vector-like superfields
• Stability of the Standard Model Vacuum with Vector-Like Leptons: A Critical Examination
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• Interplay between Vector-like Lepton and Seesaw Mechanism:Oblique Corrections
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• Singlet-Doublet Fermion Origin of Dark Matter, Neutrino Mass and W-Mass Anomaly
• From Higgs physics to lepton flavour violation: current bounds and future prospects for vector-like lepton models