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Electroweak precision constraints on vector-like fermions

  • Regular Article - Theoretical Physics
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Abstract

We calculate the oblique electroweak corrections and confront them 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 there is no mixing allowed with the standard fermions. Four electroweak parameters, \(\hat{S}\) , \(\hat{T}\) , W and Y, are presented in the formalism of Barbieri et al.; these are the generalization of the Peskin–Takeuchi S, T and U. The vector-like extension is slightly constrained. \(\hat{T}\) requires the new neutral fermion masses not to be very far from each other, allowing for higher mass differences for higher masses and smaller mixing. \(\hat{S}\) , W and Y give practically no constraints on the masses. This extension can give a positive contribution to \(\hat{T}\) , allowing for a heavy Higgs boson in electroweak precision tests of the standard model.

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Authors and Affiliations

  1. Theoretical Physics Research Group of Hungarian Academy of Sciences, Eötvös University, 1117 Pázmány Péter sétány 1/A, Budapest, Hungary

    G. Cynolter & E. Lendvai

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  1. G. Cynolter
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  2. E. Lendvai
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Correspondence to G. Cynolter.

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Cynolter, G., Lendvai, E. Electroweak precision constraints on vector-like fermions. Eur. Phys. J. C 58, 463–469 (2008). https://doi.org/10.1140/epjc/s10052-008-0771-7

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  • DOI: https://doi.org/10.1140/epjc/s10052-008-0771-7

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