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E6 inspired supersymmetric models

Howl, Richard (2009) E6 inspired supersymmetric models University of Southampton, School of Physics and Astronomy, Doctoral Thesis , 161pp.

Record type: Thesis (Doctoral)


This work investigates extensions to the Standard Model that are inspired by supersymmetric
models with an E6 gauge group. The models are non-minimal supersymmetric
theories which keep the Higgs mass stable against the quantum corrections from higher
energy physics, but do not contain the mu-problem or little hierarchy problem of the Minimal
Supersymmetric Standard Model (MSSM). Also, unlike conventional Grand Unified
Theories, the E6 inspired models do not contain any doublet-triplet splitting and the
Minimal E6 Supersymmetric Model (ME6SSM) only contains complete E6 multiplets at
low energies. A particularly exciting feature of the ME6SSM is the prediction of gauge
coupling unification at the Planck scale rather than the conventional GUT scale, hinting
at a potential unification of the Standard Model forces with quantum gravity.

If extended with a discrete non-Abelian family symmetry, the E6 inspired models
can explain the masses and mixings of the quarks and leptons that are observed in
particle experiments. These are not understood in the Standard Model since they are
free parameters, creating a
flavour problem for the theory. Extending the Standard
Model or MSSM with a family symmetry oers an attractive resolution to the
problem, and the recent discovery of neutrino oscillations, which indicate a high-level of
symmetry in the lepton mixings, has led to a renewed interest in these models. However,
explaining why the Higgs mass is small is essential in these models since it sets the scale
for the quark and lepton masses. This motivates the synthesis of a family symmetry with
the E6 inspired supersymmetric models, which resolves a number of problems facing the
Standard Model including the hierarchy problem and the
avour problem. A particular
success of the resulting models is their ability to suppress proton decay and favour
changing neutral currents, from supersymmetry and extended Higgs sectors, using the
same family symmetry that is responsible for a tri-bi-maximal mixing of leptons.

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Published date: December 2009
Organisations: University of Southampton


Local EPrints ID: 161217
PURE UUID: 8f8f545f-a7c6-4e45-bf2a-eacc34d81a80

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Date deposited: 27 Jul 2010 15:56
Last modified: 18 Jul 2017 12:34

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Author: Richard Howl
Thesis advisor: Stephen King

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