Light U(1)s in heterotic string models

Mehta, Viraf M
Light U(1)s in heterotic string models. Doctor of Philosophy thesis, University of Liverpool.

[thumbnail of Thesis_Final_Draft.pdf] PDF
Thesis_Final_Draft.pdf - Submitted version
Access to this file is embargoed until Unspecified.
After the embargo period this will be available under License Creative Commons Attribution No Derivatives.

Download (1MB)
[thumbnail of MehtaVir_Sept2013_14833.pdf] PDF
MehtaVir_Sept2013_14833.pdf - Author Accepted Manuscript
Available under License Creative Commons Attribution No Derivatives.

Download (1MB)


We present the construction of heterotic string models built using the free fermionic formulation, and focus on how additional U(1)s may arise. We motivate an anomaly free combination, U(1)_\zeta, as a proton lifetime preserving symmetry external to a left--right symmetric gauge group. This same combination is found to nullify lepton number in U(1)_{B-L} to form a leptophobic combination, also in left--right symmetric models, which we compare to other leptophobic U(1) combinations constructed in the context of different gauge groups. We then accommodate U(1)_\zeta as a proton lifeguard symmetry in an effective field theory. We present a comparative study of how gauge coupling unification constraints may be satisfied when SO(10)xU(1)_\zeta\not\subset E_6 and when the U(1)_\zeta charges do have an E_6 embedding. We show that without such an embedding, current values of \sin^2\theta_W(M_Z) and \alpha_3(M_Z) rule these models out. We go on to discuss how viable string models with this property included may be constructed.

Item Type: Thesis (Doctor of Philosophy)
Additional Information: Date: 2013-09 (completed)
Subjects: ?? QA ??
Divisions: Faculty of Science and Engineering > School of Physical Sciences > Mathematical Sciences
Depositing User: Symplectic Admin
Date Deposited: 31 Jul 2014 10:14
Last Modified: 16 Dec 2022 04:41
DOI: 10.17638/00014833
  • Faraggi, Alon E
  • Rakow, Paul EL