Dynamical models of electroweak symmetry breaking and radiative corrections
Dynamical models of electroweak symmetry breaking and radiative corrections
The development of the Standard Model of electroweak interactions is reviewed and an effective theory of these interactions below the Z mass is presented. The mass terms in the effective theory render it non-renormalizable and non-unitary highlighting the need for a gauge invariant theory of electroweak symmetry breaking. Three basic models of symmetry breaking are presented; the Higgs model and two models in which electroweak symmetry is broken dynamically, top condensation and technicolour. The dynamical models provide solutions to some of the problems associated with the Higgs theory but fail to give the light fermions masses. These models are extended by gauging the fermion family symmetry in order to generate light fermion masses. Chiral family symmetry models are introduced to suppress Flavour Changing Neutral Currents. An analysis of the energetically preferred vacuum alignment in chiral family symmetry models is performed showing that in the strong coupling regime the required vacuum is preferred.
It is shown that heavy fermions do not decouple from low energy measurements in broken gauge theories but contribute to radiative corrections below their mass threshold. Recent high energy collider and low energy atomic measurements have reached the levels of precision necessary to see these effects in the Standard Model. The effects of these radiative corrections in the Standard Model can be parameterized in terms of two variables S and T. The contributions to the precision parameters S and T from the simplest dynamical models of electroweak symmetry breaking are calculated in a Non Local Chiral Model of the strong, confining interactions. The effects of custodial isospin breaking in extended dynamical models is incorporated as perturbations to the Non Local Chiral Model and where that approximation fails Dynamical Perturbation Theory is used. The parameters S and T are estimated in dynamical models with Majorana neutrino masses. Finally some realistic mass spectra are presented in extended dynamical models.
University of Southampton
1993
Evans, Nicholas John
(1993)
Dynamical models of electroweak symmetry breaking and radiative corrections.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The development of the Standard Model of electroweak interactions is reviewed and an effective theory of these interactions below the Z mass is presented. The mass terms in the effective theory render it non-renormalizable and non-unitary highlighting the need for a gauge invariant theory of electroweak symmetry breaking. Three basic models of symmetry breaking are presented; the Higgs model and two models in which electroweak symmetry is broken dynamically, top condensation and technicolour. The dynamical models provide solutions to some of the problems associated with the Higgs theory but fail to give the light fermions masses. These models are extended by gauging the fermion family symmetry in order to generate light fermion masses. Chiral family symmetry models are introduced to suppress Flavour Changing Neutral Currents. An analysis of the energetically preferred vacuum alignment in chiral family symmetry models is performed showing that in the strong coupling regime the required vacuum is preferred.
It is shown that heavy fermions do not decouple from low energy measurements in broken gauge theories but contribute to radiative corrections below their mass threshold. Recent high energy collider and low energy atomic measurements have reached the levels of precision necessary to see these effects in the Standard Model. The effects of these radiative corrections in the Standard Model can be parameterized in terms of two variables S and T. The contributions to the precision parameters S and T from the simplest dynamical models of electroweak symmetry breaking are calculated in a Non Local Chiral Model of the strong, confining interactions. The effects of custodial isospin breaking in extended dynamical models is incorporated as perturbations to the Non Local Chiral Model and where that approximation fails Dynamical Perturbation Theory is used. The parameters S and T are estimated in dynamical models with Majorana neutrino masses. Finally some realistic mass spectra are presented in extended dynamical models.
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Published date: 1993
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Local EPrints ID: 462426
URI: http://eprints.soton.ac.uk/id/eprint/462426
PURE UUID: f2b6b52b-d86d-4ec5-99ab-43dbce97f006
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Date deposited: 04 Jul 2022 19:07
Last modified: 04 Jul 2022 19:07
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Author:
Nicholas John Evans
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