Binoth, Thomas

Gardi, Einan

Boyle, Peter

Pendleton, Brian

Carrington, James Michael

Science and Technology Facilities Council (STFC)

2014-05-26T15:11:59Z

2014-05-26T15:11:59Z

2013-11-28

The Standard Model scalar potential contains a minimum at the Electroweak scale, responsible for the masses of the weak gauge bosons through the Higgs mechanism. However, if the Electroweak minimum is only a local minimum, and there exists a global minimum at a higher energy in the Higgs potential, then in a su ciently old universe we would expect the vacuum expectation value to be at the global minimum. The absence of a global minimum at higher energy is related to the condition that the Higgs self coupling is greater than or equal to zero for all energies. For any model that fails this, we expect new physics to enter before the energy at which the coupling becomes negative. We developed tools to automate the derivation of beta functions for renormalisable gauge theories, and used these to carry out evolution of the renormalisation group equations for the Standard Model and three extensions to the Standard Model | the Standard Model with a fourth generation, the Standard Model with right-handed neutrinos and a Left-Right Symmetric Model. We conclude that of these four models, the Standard Model is the only one in which all the couplings remain perturbative, and in which the Electroweak minimum is a global minimum.

http://hdl.handle.net/1842/8851

en

The University of Edinburgh

coupling strength

beta functions

Standard Model couplings

weak gauge bosons

Higgs mechanism

Higgs self coupling

Electroweak minimum

Vacuum stability of the standard model and BSM extensions

Thesis or Dissertation

Doctoral

PhD Doctor of Philosophy