Gauge-Higgs unification on the brane

From the quantum field theory point of view, matter and gauge fields are generally expected to be localised around branes or topological defects occurring in extra dimensions. Here I discuss a simple scenario where, by starting with a five dimensional SU(3) gauge theory, we end up with several 4-D parallel branes with localised "chiral" fermions and gauge fields to them. I will show that it is possible to reproduce the electroweak model confined to a single brane, allowing a simple and geometrical approach to the fermion hierarchy problem. Some nice results of this construction are: Gauge and Higgs fields are unified at the 5-D level; and new particles are predicted: a left-handed neutrino of zero hypercharge, and a massive vector field coupling together the new neutrino to other left-handed leptons.Comment: Contribution to the proceedings of the RTN workshop "The Quest for Unification: Theory Confronts Experiment", Corfu, Greece, Sept 11-18, 200

Towards common origin of supersymmetry breaking, compositeness, and gauge mediation

We present a toy model which has the following properties: i) it is strongly coupled at a certain scale and breaks supersymmetry at this scale; ii) matter superfields of (one generation of) the Standard Model are effective low energy degrees of freedom of this strongly coupled theory; iii) direct gauge mediation of supersymmetry breaking occurs due to messenger superfields that are also effective low energy degrees of freedom. We discuss the way to generalize this approach to realistic models with three generations. These models might be favorable from the point of view of string theory compactifications.Comment: 7 pages, LaTeX, no figures; grant numbers correcte

Gauge theory solitons on noncommutative cylinder

We generalize to noncommutative cylinder the solution generation technique, originally suggested for gauge theories on noncommutative plane. For this purpose we construct partial isometry operators and complete set of orthogonal projectors in the algebra of the cylinder, and an isomorphism between the free module and its direct sum with the Fock module on the cylinder. We construct explicitly the gauge theory soliton and evaluate the spectrum of perturbations about this soliton.Comment: References added; to appear in Theor.Math.Phy

Quasilocalized gravity without asymptotic flatness

We present a toy model of a generic five-dimensional warped geometry in which the 4D graviton is not fully localized on the brane. Studying the tensor sector of metric perturbation around this background, we find that its contribution to the effective gravitational potential is of 4D type (1/r) at the intermediate scales and that at the large scales it becomes 1/r^{1+alpha}, 0<alpha=< 1 being a function of the parameters of the model (alpha=1 corresponds to the asymptotically flat geometry). Large-distance behavior of the potential is therefore not necessarily five-dimensional. Our analysis applies also to the case of quasilocalized massless particles other than graviton.Comment: 9 pages, 1 figure; to be published in Phys. Rev.