arXiv subjects

G. Zoupanos

Publications and source records attributed to G. Zoupanos.

51 records · Page 3Linked to original sources

arXiv2004

Finite Unified Theories and the Higgs mass prediction

Finite Unified Theories (FUTs) are N=1 supersymmetric Grand Unified Theories, which can be made all-loop finite, both in the dimensionless (gauge and Yukawa couplings) and dimensionful (soft supersymmetry breaking terms) sectors. This remarkable property provides a drastic reduction in the number of free parameters, which in turn leads to an accurate prediction of the top quark mass in the dimensionless sector, and predictions for the Higgs boson mass and the supersymmetric spectrum in the dimensionful sector. Here we examine the predictions of two FUTs taking into account a number of theoretical and experimental constraints. For the first one we present the results of a detailed scanning concerning the Higgs mass prediction, while for the second we present a representative prediction of its spectrum.

hep-ph↗

arXiv2004

Unified Theories from Fuzzy Extra Dimensions

We combine and exploit ideas from Coset Space Dimensional Reduction (CSDR) methods and Non-commutative Geometry. We consider the dimensional reduction of gauge theories defined in high dimensions where the compact directions are a fuzzy space (matrix manifold). In the CSDR one assumes that the form of space-time is M^D=M^4 x S/R with S/R a homogeneous space. Then a gauge theory with gauge group G defined on M^D can be dimensionally reduced to M^4 in an elegant way using the symmetries of S/R, in particular the resulting four dimensional gauge is a subgroup of G. In the present work we show that one can apply the CSDR ideas in the case where the compact part of the space-time is a finite approximation of the homogeneous space S/R, i.e. a fuzzy coset. In particular we study the fuzzy sphere case.

hep-th↗

arXiv2002

Non-Kaehler String Backgrounds and their Five Torsion Classes

We discuss the mathematical properties of six--dimensional non--Kähler manifolds which occur in the context of ${\cal N}=1$ supersymmetric heterotic and type IIA string compactifications with non--vanishing background H--field. The intrinsic torsion of the associated SU(3) structures falls into five different classes. For heterotic compactifications we present an explicit dictionary between the supersymmetry conditions and these five torsion classes. We show that the non--Ricci flat Iwasawa manifold solves the supersymmetry conditions with non--zero H--field, so that it is a consistent heterotic supersymmetric groundstate.

hep-th↗

arXiv2002

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.

hep-ph↗

arXiv2002

Dimensional Reduction over Coset Spaces and Supersymmetry Breaking

We address the question of supersymmetry breaking of a higher dimensional supersymmetric theory due to coset space dimensional reduction. In particular we study a ten-dimensional supersymmetric $E_{8}$ gauge theory which is reduced over all six-dimensional coset spaces. We find that the original supersymmetry is completely broken in the process of dimensional reduction when the coset spaces are symmetric. On the contrary softly broken four-dimensional supersymmetric theories result when the coset spaces are non-symmetric. From our analysis two promising cases are emerging which lead to interesting GUTs with three fermion families in four dimensions, one being non-supersymmetric and the other softly broken supersymmetric.

hep-ph↗

arXiv2001

Soft Supersymmetry Breaking due to Dimensional Reduction over Non-Symmetric Coset Spaces

A ten-dimensional supersymmetric $E_8$ gauge theory is compactified over six-dimensional coset spaces, establishing further our earlier conjecture that the resulting four dimensional theory is a softly broken supersymmetric gauge theory in the case that the used coset space is non-symmetric. The specific non-symmetric six-dimensional spaces examined in the present study are $Sp(4)/(SU(2) \times U(1))_{non-max.}$ and $ SU(3)/U(1) \times U(1)$.

hep-ph↗

arXiv2000

Supersymmetry Breaking by Dimensional Reduction over Coset Spaces

We study the dimensional reduction of a ten-dimensional supersymmetric E_8 gauge theory over six-dimensional coset spaces. We find that the coset space dimensional reduction over a symmetric coset space leaves the four dimensional gauge theory without any track of the original supersymmetry. On the contrary the dimensional reduction over a non symmetric coset space leads to a softly broken supersymmetric gauge theory in four dimensions. The SO_7/SO_6 and G_2/SU(3) are used as representative prototypes of symmetric and non symmetric coset spaces respectively.

hep-ph↗

arXiv1998

Gauge-Yukawa-Finite Unified Theories and their Predictions

Gauge-Yukawa unified theories, and in particular those which are finite beyond the unification scale, have been extended to include a soft supersymmetry breaking (SSB) sector. In the case of the Finite Unified Theories a new solution to the condition of two-loop finiteness of the SSB parameters is found, which requires a sum rule for the relevant scalar masses. The sum rule permits violations of the universality of the scalar masses which is found to lead to phenomenological problems. The minimal supersymmetric SU(5) Gauge-Yukawa model and two Finite-Gauge-Yukawa models have been examined using the sum rule. The characteristic features of these models are: a) the old agreement of the top quark mass prediction persists using the new data, b) the lightest Higgs boson is predicted to be around 120 GeV, c) the s-spectrum starts above 200 GeV.

hep-ph↗

arXiv1997

Constraints on Finite Soft Supersymmetry-Breaking Terms

Requiring the soft supersymmetry-breaking (SSB) parameters in finite gauge-Yukawa unified models to be finite up to and including two-loop order, we derive a two-loop sum rule for the soft scalar-masses. It is shown that this sum rule coincides with that of a certain class of string models in which the massive string states are organized into N=4 supermultiplets. We investigate the SSB sector of two finite SU(5) models. Using the sum rule which allows the non-universality of the SSB terms and requiring that the lightest superparticle particleis neutral, we constrain the parameter space of the SSB sector in each model.

hep-ph↗

arXiv1997

Reduction of Couplings and Finiteness in Realistic Supersymmetric GUTs

Reduction of couplings in supersymmetric GUTs is achieved by searching for renormalization group invariant (RGI) relations among couplings which hold beyond the unification scale. Finiteness is due to the fact that there exist RGI relations among couplings that guarantee the vanishing of the beta-functions of a N=1 supersymmetric GUT even to all orders in perturbation theory. Of particular interest are the relations among gauge and Yukawa couplings which lead to very interesting predictions of the top quark mass

hep-ph↗

arXiv1997

Unification Beyond GUTs: Gauge-Yukawa Unification

Gauge-Yukawa Unification (GYU) is a renormalization group invariant functional relation among gauge and Yukawa couplings which holds beyond the unification point in Grand Unified Theories (GUTs). We present here various models where GYU is obtained by requiring the principles of finiteness and reduction of couplings. We examine the consequences of these requirements for the low energy parameters, especially for the top quark mass. The predictions are such that they clearly distinguish already GYU from ordinary GUTs. It is expected that it will be possible to discriminate among the various GYUs when more accurate measurements of the top quark mass are available.

hep-ph↗

arXiv1997

Gauge-Yukawa Unified Models

Gauge-Yukawa Unification (GYU) is obtained in GUTs by searching for renormalization group invariant relations among gauge and Yukawa couplings beyond the unification scale. Of particular interest are two supersymmetric GUTs, the finite and the minimal SU(5) models. Both models provided us,among others,with predictions of the top quark mass which so far have passed successfully the tests of progressively more accurate measurements.

hep-ph↗

arXiv1996

All-order Finiteness in N=1 SYM Theories: Criteria and Applications

As a motivation, we first recall the possible connection of electric-magnetic duality to finiteness in N=1 super-Yang-Mills theories (SYM). Then, we present the criterion for all-order finiteness (i.e., vanishing of the beta-functions at all orders) in N=1 SYM. Finally, we apply this finiteness criterion to an SU(5) SGUT. The latter turns out to be all-order finite if one imposes additional symmetries.

hep-ph↗

arXiv1995

LINEAR CONNECTIONS ON EXTENDED SPACE-TIME

A modification of Kaluza-Klein theory is proposed which is general enough to admit an arbitrary finite noncommutative internal geometry. It is shown that the existence of a non-trival extension to the total geometry of a linear connection on space-time places severe restrictions on the structure of the noncommutative factor. A counter-example is given.

hep-th↗

arXiv1992

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.

hep-ph↗