Related papers: Grand Unified Theories From Superstrings
We discuss a grand unified theory (GUT) based on an $SO(32)$ GUT gauge group broken to its subgroups including a special subgroup. In the $SO(32)$ GUT on six-dimensional (6D) orbifold space $M^4\times T^2/\mathbb{Z}_2$, one generation of…
A generic heterotic string theory is uniquely reduced to the standard model in terms of a geometry that transcends compactification. This device also extends the standard model to embrace three generations of fermions, including a…
We propose an $SO(10)$ supersymmetric grand unified theory (SUSY GUT), where the $SO(10)$ gauge symmetry breaks down to $SU(3)_c \times SU(2)_L \times U(1)_Y\times U(1)_{X}$ at the GUT scale and $U(1)_X$ is radiatively broken at the…
In this thesis we investigate the microphysics of cosmic strings in non-minimal quantum field theories. In particular we consider theories in which fermion fields couple to the strings, and those with larger symmetry groups, such as grand…
Grand gauge-Higgs unification of five dimensional SU(6) gauge theory on an orbifold $S^1 / Z_2$ with localized gauge kinetic terms is discussed. The Standard model (SM) fermions on the boundaries and some massive bulk fermions coupling to…
I discuss several aspects of strings as unified theories. After recalling the difficulties of the simplest supersymmetric grand unification schemes I emphasize the distinct features of string unification. An important role in constraining…
Grand unification groups (GUTs) are constructed from SO(32) heterotic string via $\Z_{12-I}$ orbifold compactification. So far, most phenomenological studies from string compactification relied on $\EE8$ heterotic string, and this invites…
In this talk~\footnote{Talk presented at the IFT Workshop on Yukawa Couplings, Gainesville, FL, February 1994.} I summarize published work on a systematic operator analysis for fermion masses in a class of effective supersymmetric SO(10)…
We present a self-consistent $\chi^2$ analysis of several supersymmetric (SUSY) grand unified theories recently discussed in the literature. We obtain global fits to low energy data, including gauge couplings, fermion masses and mixing…
We investigate a large class of supersymmetric SO(10) grand unified theories within the framework of gauge-mediated supersymmetry breaking. We start with the most general messenger sector and imbedd the standard model gauge group into…
We consider a minimal non-supersymmetric $SO(10)$ Grand Unified Theory (GUT) model that can reproduce the observed fermionic masses and mixing parameters of the Standard Model. We calculate the scales of spontaneous symmetry breaking from…
The GUT-based approach to physics has been attractive since it was first put forward close to thirty years ago; it has been enriched by new ideas, notably supersymmetry and strings; and there are real hints that it is on the right track,…
The interpretation of the apparent unification of gauge couplings within supersymmetric theories depends on uncertainties induced through heavy particle thresholds. While in standard grand unified theories these effects can be estimated…
In this Honours Research Project the aim is to build a toy model of an SO(10) Grand Unified Theory with an extra spatial dimension. Utilising the Clash of Symmetries mechanism proposed for brane-world models by Davidson, Toner, Volkas and…
We discuss the unification of gauge couplings within the framework of a wide class of realistic free-fermionic string models which have appeared in the literature, including the flipped SU(5), SO(6)xSO(4), and various SU(3)xSU(2)xU(1)…
The conventional supersymmetric grand unified theories suffer from two serious problems, the large mass splitting between doublet and triplet Higgs multiplets, and the too long lifetime of the proton. A unification model based on a…
This is a pedagogical review article surveying the various approaches towards understanding gauge coupling unification within string theory. As is well known, one of the major problems confronting string phenomenology has been an apparent…
Grand unified models in four dimensions typically suffer from the doublet-triplet splitting problem. This obstacle can be overcome in higher-dimensional settings, where a non-trivial gauge group topography can explain the simultaneous…
Grand Unified Theories (GUTs) are a very well motivated extensions of the Standard Model (SM), but the landscape of models and possibilities is overwhelming, and different patterns can lead to rather distinct phenomenologies. In this work…
Grand unified theory defined on higher-dimensional orbifolds provides a new way to solve the hierarchy problem. In gauge theory on an orbifold many different sets of boundary conditions imposed at orbifold fixed points (branes) are related…