Related papers: Supersymmetric Grand Unification
We study the supersymmetric spontaneous symmetry breaking of SO(10) into SU(3)xSU(2)xU(1) for the most physically interesting cases of SU(5) or flipped SU(5)xU(1) intermediate symmetries. The first case is more easily realized while the…
The connection between the scales of $ {\rm SU} (2)\times {\rm U} (1) $ gauge symmetry breaking and supersymmetry breaking is didactically displayed in the framework of a T.O.Y. (Theory Overestimating Yukawas) model, a version of the $…
We investigate the presence of discrete gauge symmetries in Grand Unification models based in $SO(10)$ and $E_6$. These models include {\it flipped} and {\it unflipped} $SU(5)$, $SU(4)\!\times\! SU(2)_L\!\times\! SU(2)_R$,…
We explore the phenomenology of the minimal supersymmetric flipped SU(5) GUT model (CFSU(5)), whose soft supersymmetry-breaking (SSB) mass parameters are constrained to be universal at some input scale, $M_{in}$, above the GUT scale,…
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…
We analyze nucleon decay modes in a no-scale supersymmetric flipped SU(5) GUT model, and contrast them with the predictions for proton decays via dimension-6 operators in a standard unflipped supersymmetric SU(5) GUT model. We find that…
We study in detail the structure of Grand Unified Theories derived as the low-energy limit of orbifold four-dimensional strings. To this aim, new techniques for building level-two symmetric orbifold theories are presented. New classes of…
These lectures provide a self-contained introduction to the essential aspects of non-supersymmetric beyond the Standard Model (BSM) physics for beginning graduate students who are already familiar with quantum field theory. After a detailed…
The proton decay in supersymmetric (SUSY) Grand Unified Theories (GUTs), where the special mechanism provides the natural suppression of the dimension 5 ($d=5$) operators, was studied. Due to this mechanism, $d=5$ operator induced proton…
We consider generalizations of the standard model (SM) which are based on the gauge symmetry $SU(n)_c\otimes SU(m)_L\otimes U(1)_N$. Although the most interesting possibilities occur when $n=3$, we will consider also the cases $n=4,5$ both…
The standard model (SM) of particle physics is for the last three decades a very successful description of the properties and interactions of all known elementary particles. Currently, it is again probed with the first collisions at the…
We investigate the SU(N) supersymmetric Grand Unified Theories with ``custodial symmetry'' mechanism to explane the doublet-triplet hierarchy. We show that in such type of SU(7) SUSY theory intermediate scale appears naturally and the…
Grand Unified Theories (GUTs) are attractive candidates for more fundamental elementary particle theories. They can not only unify the Standard Model (SM) interactions but also different types of SM fermions, in particular quarks and…
I discuss several issues concerning the use of string models as unified theories of all interactions. After a short review of gauge coupling unification in the string context, I discuss possible motivations for the construction of $SU(5)$…
The Standard Model of particle physics may seem complicated and arbitrary, but it has hidden patterns that are revealed by the relationship between three "grand unified theories": theories that unify forces and particles by extending the…
We present a grand unified model based on the supersymmetric $SU(3)_L\otimes SU(3)_{CL}\otimes SU(3)_{CR}\otimes SU(3)_R$ gauge group, which unifies in one single step the three gauge couplings of the standard model at an scale $M\sim…
A brief overview of Grand Unified Models is presented with some attention paid to their predictions for neutrino oscillations. Given the well-known features of the two non-unified standard models, SM and MSSM, a listing of the features of…
The unification of gauge coupling constants in the minimal supersymmetric model (MSSM) is unaffected at the one-loop level by the inclusion of additional mass-degenerate SU(5) multiplets. Perturbativity puts an upper limit on the number of…
We revisit the Missing Doublet Model (MDM) as a means to address the apparent difficulties of the minimal $SU(5)$ supergravity model in dealing with the doublet-triplet splitting problem, the prediction of $\alpha_3(M_Z)$, and the proton…
We consider the possibility of grand unification of the $\mathrm{ SU(3)_c \otimes SU(3)_L \otimes U(1)_X}$ model in an SU(6) gauge unification group. Two possibilities arise. Unlike other conventional grand unified theories, in SU(6) one…