Use this URL to cite or link to this record in EThOS:
Title: Classification of quasi-realistic heterotic string vacua
Author: Harries, Glyn
ISNI:       0000 0004 7656 9914
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2019
Availability of Full Text:
Access from EThOS:
Access from Institution:
The free fermionic formulation of heterotic strings has been able to provide some of the most phenomenologically viable string models to date. Within this formulation, classifications of string models with an SO(10) GUT embedding and its subgroups have been shown to admit three chiral generations of matter, necessary Higgs representations and various other aspects of phenomenology associated with the Standard Model. The classification method is extended to models where the SO(10) symmetry is broken directly at the string scale to the Left-Right Symmetric subgroup. The method involves defining a set of basis vectors where fixed boundary conditions are assigned to the free fermions, before exploring the string vacua generated by varying the Generalised GSO (GGSO) projection coefficients. The method admits the derivation of algebraic expressions for each of the GGSO projections on a sector in order to generate the complete massless spectrum of the models. The derived algebraic expressions can be written in a computer code so as to facilitate a computerised analysis of the entire spectrum for each choice of GGSO projection coefficients. The classification procedure has been previously applied to models with the following subgroups of the observable SO(10) gauge group: SO(6) x SO(4) (Pati-Salam), SU(5) x U(1) (Flipped SU(5)), SU(4) x SU(2) x U(1) (SU(421)) and SU(3) x SU(2) x U(1)2 (Standard-like Models). A statistical sampling of models with the Left-Right Symmetric observable gauge group is performed and the results are presented. In contrast to the previous classification of Pati-Salam models, no three generation exophobic vacua were found. However, contrary to the SU(421) case which was found to be overconstrained and no complete generations of matter exist, complete generations of matter were found to exist for the Left-Right Symmetric case. The results of the classification performed demonstrate the existence of Left-Right Symmetric models with three chiral generations of matter, the necessary Higgs representations for spontaneous symmetry breaking and a leading top quark Yukawa coupling.
Supervisor: Faraggi, Alon Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral