Soft Supersymmetry Breaking from Coset Space Dimensional Reduction

The Coset Space Dimensional Reduction scheme is briefly reviewed. Then a ten-dimensional supersymmetric $E_8$ gauge theory is reduced over symmetric and non-symmetric six-dimensional coset spaces. In general a four-dimensional non-supersymmetric gauge theory is obtained in case the used coset space is symmetric, while a softly broken supersymmetric gauge theory is obtained if the used coset space is non-symmetric. In the process of exhibiting the above properties we also present two attractive models, worth exploiting further, which lead to interesting GUTs with three families in four dimensions.Comment: 16 pages, Contribution to SUSY01 Dubna Russia, CORFU2001 Corfu Greece, SQS01 Karpacz Poland and I Summer School in Modern Mathematical Physics Sokobanja Yugoslavi

Dimensional Reduction of ten-dimensional Supersymmetric Gauge Theories in the N=1, D=4 Superfield Formalism

A ten-dimensional supersymmetric gauge theory is written in terms of N=1, D=4 superfields. The theory is dimensionally reduced over six-dimensional coset spaces. We find that the resulting four-dimensional theory is either a softly broken N=1 supersymmetric gauge theory or a non-supersymmetric gauge theory depending on whether the coset spaces used in the reduction are non-symmetric or symmetric. In both cases examples susceptible to yield realistic models are presented.Comment: 24 page

Confronting Finite Unified Theories with Low-Energy Phenomenology

Finite Unified Theories (FUTs) are N=1 supersymmetric Grand Unified Theories that can be made all-loop finite. The requirement of all-loop finiteness leads to a severe reduction of the free parameters of the theory and, in turn, to a large number of predictions. FUTs are investigated in the context of low-energy phenomenology observables. We present a detailed scanning of the all-loop finite SU(5) FUTs, where we include the theoretical uncertainties at the unification scale and we apply several phenomenological constraints. Taking into account the restrictions from the top and bottom quark masses, we can discriminate between different models. Including further low-energy constraints such as B physics observables, the bound on the lightest Higgs boson mass and the cold dark matter density, we determine the predictions of the allowed parameter space for the Higgs boson sector and the supersymmetric particle spectrum of the selected model.Comment: 25 pages, 8 figures. Discussion on models and on cold dark matter constraint extended, references added. Version to appear in JHE

Finite Unified Theories confronted with low-energy phenomenology

Finite Unified Theories (FUTs) are N=1 supersymmetric Grand Unified Theories that can be made all-loop finite. The requirement of all-loop finiteness leads to a severe reduction of the free parameters of the theory and, in turn, to a large number of predictions. Here SU(5) FUTs are investigated in the context of low-energy phenomenology observables. We present a detailed scanning of these FUTs, including theoretical uncertainties at the unification scale and applying all phenomenological constraints. Taking into account the restrictions from the top and bottom quark masses, we can discriminate between different models. Including further low-energy constraints such as $B$ physics observables, the bound on the lightest Higgs boson mass and the cold dark matter density, we determine the predictions of the allowed parameter space for the Higgs boson sector and the supersymmetric particle spectrum of the model.Comment: Submitted for the SUSY07 proceedings, 4 pages, LaTeX, 3 eps figures. v2 one ref adde

Finite Unified Models

We present phenomenologically viable $SU(5)$ unified models which are finite to all orders before the spontaneous symmetry breaking. In the case of two models with three families the top quark mass is predicted to be 178.8 GeV.Comment: 13 pages, latex fil

Finite Theories after the discovery of a Higgs-like boson at the LHC

Finite Unified Theories (FUTs) are N = 1 supersymmetric Grand Unified Theories (GUTs) which can be made finite to all-loop orders, based on the principle of reduction of couplings, and therefore are provided with a large predictive power. Confronting the predictions of SU(5) FUTs with the top and bottom quark masses and other low-energy experimental constraints a light Higgs-boson mass in the range M_h ~ 121-126 GeV was predicted, in striking agreement with the recent discovery of a Higgs-like state around ~ 125.7 GeV at ATLAS and CMS. Furthermore the favoured model, a finiteness constrained version of the MSSM, naturally predicts a relatively heavy spectrum with coloured supersymmetric particles above ~ 1.5 TeV, consistent with the non-observation of those particles at the LHC. Restricting further the best FUT's parameter space according to the discovery of a Higgs-like state and B-physics observables we find predictions for the rest of the Higgs masses and the s-spectrum.Comment: 17 pages, 4 figures. arXiv admin note: substantial text overlap with arXiv:0712.363