Related papers: Gauge Coupling Unification in Realistic Free-Fermi…
We propose gauging matrix models of string theory to eliminate unwanted non-singlet states. To this end we perform a discretised light-cone quantisation of large N gauge theory in 1+1 dimensions, with scalar or fermionic matter fields…
The string landscape suggests that the supersymmetry breaking scale can be high, and then the simplest low energy effective theory is the Standard Model (SM). We show that gauge coupling unification can be achieved at about 10^{16-17} GeV…
We examine unification of gauge couplings in four dimensional renormalizable gauge theories inspired by the latticized (deconstructed) SM or MSSM in five dimensions. The models are based on replicated gauge groups, spontaneously broken to…
I review the unification of gauge couplings of strong, weak and electro-magnetic interactions. I start by recalling the history of the most important prediction of low-energy supersymmetry: the correct value of the weak mixing angle tied 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…
After reviewing the general structure of supersymmetric intersecting brane world models, we discuss the issue of stringy gauge coupling unification for a natural class of MSSM-like models.
We revisit the question of gauge coupling unification at the string scale in orbifold compactifications of the heterotic string for the supersymmetric Standard Model. In the presence of discrete Wilson lines threshold corrections with…
We analyze approaches to the partial or complete unification of gauge symmetries in theories with dynamical symmetry breaking. Several types of models are considered, including those that (i) involve sufficient unification to quantize…
One of the much-debated novel features of theories with extra dimensions is the presence of power-like loop corrections to gauge coupling unification, which have the potential of allowing a significant reduction of the unification scale. A…
We consider the renormalisation group flow of gauge couplings within the so-called exceptional supersymmetric standard model (E$_6$SSM) based on the low energy matter content of 27 dimensional representations of the gauge group $E_6$,…
In this paper we study the influence of the threshold effects due to massive degrees of freedom in the evolution with scale of gauge coupling constants. We first describe in detail the (standard) mass dependent renormalization prescription…
Because of the problems arising from the fermion unification in the traditional Grand Unified Theory and the mass hierarchy between the 4-dimensional Planck scale and weak scale, we suggest the low energy gauge unification theory with low…
We explore possibilities of gauge coupling unification in left--right symmetric models with non--minimal particle content. In addition to unification we require the absence of anomalies and sufficient proton lifetime. Numerous previously…
One of the drawbacks of conventional grand unification scenarios has been that the unification scale is too high to permit direct exploration. In this paper, we show that the unification scale can be significantly lowered (perhaps even to…
We investigate constraints that the requirements of perturbativity and gauge coupling unification impose on extensions of the Standard Model and of the MSSM. In particular, we discuss the renormalization group running in several SUSY…
We investigate gauge coupling unification for F-theory respectively Type IIB orientifold constructions of SU(5) GUT theories with gauge symmetry breaking via non-trivial hypercharge flux. This flux has the non-trivial effect that it splits…
It is well-known that heterotic string compactifications have, in spite of their conceptual simplicity and aesthetic appeal, a serious problem with precision gauge coupling unification in the perturbative regime of string theory. Using both…
We construct and analyze an $SU(6)\times SU(2)$ GUT. The model is k=1 string embedable in the sense that we employ only chiral representations allowed at the k=1 level of the associated Ka\v{c}-Moody Algebra. Both cases $SU(6)\times…
We investigate gauge coupling unification at 2-loops for theories with 5 extra vectorlike SU(5) fundamentals added to the MSSM. This is a borderline case where unification is only predicted in certain regions of parameter space. We…
We explore the possibility of unification of gauge couplings near the Planck scale in models of extended technicolor. We observe that models of the form G X SU(3)_c X SU(2)_L X U(1)_Y cannot be realized, due to the presence of massless…