Related papers: Effect of Extra Dimensions on Gauge Coupling Unifi…
Extra-dimensions are a common topic in popular descriptions of theoretical physics with which undergraduate student most often have no contact in physics courses. This paper shows how students could be introduced to this topic by presenting…
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…
I discuss gauge coupling unification in a class of superstring standard--like models, which are derived in the free fermionic formulation. Recent calculations indicate that the superstring unification scale is at $O(10^{18}GeV)$ while the…
We explore the gauge coupling relations and the unification scale in F-theory SU(5) GUT broken down to the Standard Model by an internal U(1)Y gauge flux. We consider variants with exotic matter representations which may appear in these…
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 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 the…
We show how the tree level unitarity violations of compactified extra dimensional extensions of the Standard Model become much stronger when the scalar sector is included in the bulk. This effect occurs when the couplings are not suppressed…
In theories with TeV string scale and sub-millimeter extra dimensions the attractive picture of logarithmic gauge coupling unification at $10^{16}$ GeV is seemingly destroyed. In this paper we argue to the contrary that logarithmic…
Additional U(1) gauge symmetries and corresponding vector bosons, called hidden photons, interacting with the regular photon via kinetic mixing are well motivated in extensions of the Standard Model. Such extensions often exhibit extra…
The presence of an extra dimension of size R \approx TeV^{-1} introduces a tower of Kaluza-Klein gauge boson excitations that affects the standard model (SM) relations between electroweak observables. The mixing of the W and Z bosons with…
The consequences of large radius extra space-time compactified dimensions on the four dimensional one loop effective potential are investigated for a model which includes scalar self interactions and Yukawa coupling to fermions. The…
When the extra dimensional space is not simply-connected, dynamics of the AB phase in the extra dimension can induce dynamical gauge symmetry breaking by the Hosotani mechanism. This opens up a new way of achieving unification of gauge…
We consider the possibility of gauge bosons living in the recently proposed five-dimensional theory with localized gravity. We study the mass spectrum of the Kaluza-Klein (KK) excitations of the gauge fields and calculate their couplings to…
Effects of Kaluza-Klein excitations associated with extra dimensions with large radius compactifications on the Fermi constant are explored. It is shown that the current precision determinations of the Fermi constant, of the fine structure…
We have recently proposed an alternative picture for the physics at the scale of gauge coupling unification, where the unified symmetry is realized in higher dimensions but is broken locally by a symmetry breaking defect. Gauge coupling…
We examine gauge theories defined in higher dimensions where theextra dimensions form a fuzzy (finite matrix) manifold. First we reinterpret these gauge theories as four-dimensional theories with Kaluza-Klein modes and then we perform a…
In scenarios motivated by string theories, it is possible to have extra Kaluza-Klein dimensions compactified to rather large magnitudes, leading to large effects of gravity at scales down to a TeV. The effect of the spin-2 Kaluza-Klein…
Much recent attention has focused on theories with large extra compactified dimensions. However, while the phenomenological implications of the volume moduli associated with such compactifications are well understood, relatively little…
In this talk I discuss the problems and virtues of SUSY GUTs in four dimensions. I then show how to solve some of these problems, without foregoing the virtues, by considering an SO(10) SUSY GUT in five dimensions. I discuss gauge coupling…
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…