63 research outputs found
Soft Supersymmetry Breaking from Coset Space Dimensional Reduction
The Coset Space Dimensional Reduction scheme is briefly reviewed. Then a
ten-dimensional supersymmetric 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
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.Comment: 6 pages, Invited talk given by G. Zoupanos at the 36th International
Symposium Ahrenshoop, Wernsdorf, Germany, 26-30 Aug 200
Gravity as a Gauge Theory on Three-Dimensional Noncommutative spaces
We plan to translate the successful description of three-dimensional gravity
as a gauge theory in the noncommutative framework, making use of the covariant
coordinates. We consider two specific three-dimensional fuzzy spaces based on
SU(2) and SU(1,1), which carry appropriate symmetry groups. These are the
groups we are going to gauge in order to result with the transformations of the
gauge fields (dreibein, spin connection and two extra Maxwell fields due to
noncommutativity), their corresponding curvatures and eventually determine the
action and the equations of motion. Finally, we verify their connection to
three-dimensional gravity.Comment: arXiv admin note: text overlap with arXiv:1802.0755
Fuzzy Extra Dimensions: Dimensional Reduction, Dynamical Generation and Renormalizability
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 generalized \`a la Forgacs-Manton dimensional reduction. We emphasize
some striking features emerging in the later case such as (i) the appearance of
non-abelian gauge theories in four dimensions starting from an abelian gauge
theory in higher dimensions, (ii) the fact that the spontaneous symmetry
breaking of the theory takes place entirely in the extra dimensions and (iii)
the renormalizability of the theory both in higher as well as in four
dimensions. Then reversing the above approach we present a renormalizable four
dimensional SU(N) gauge theory with a suitable multiplet of scalar fields,
which via spontaneous symmetry breaking dynamically develops extra dimensions
in the form of a fuzzy sphere. We explicitly find the tower of massive
Kaluza-Klein modes consistent with an interpretation as gauge theory on , the scalars being interpreted as gauge fields on . Depending
on the parameters of the model the low-energy gauge group can be of the form
.Comment: 18 pages, Based on invited talks presented at various conferences,
Minor corrections, Acknowledgements adde
Can noncommutativity resolve the Big-Bang singularity?
A possible way to resolve the singularities of general relativity is proposed
based on the assumption that the description of space-time using commuting
coordinates is not valid above a certain fundamental scale. Beyond that scale
it is assumed that the space-time has noncommutative structure leading in turn
to a resolution of the singularity. As a first attempt towards realizing the
above programme a modification of the Kasner metric is constructed which is
commutative only at large time scales. At small time scales, near the
singularity, the commutation relations among the space coordinates diverge. We
interpret this result as meaning that the singularity has been completely
delocalized.Comment: Latex, 13 pages, 2 figures, accepted for publication in EPJ
Fluxes, Gaugings and Gaugino Condensates
Based on the correspondence between the N = 1 superstring compactifications
with fluxes and the N = 4 gauged supergravities, we study effective N = 1
four-dimensional supergravity potentials arising from fluxes and gaugino
condensates in the framework of orbifold limits of (generalized) Calabi-Yau
compactifications. We give examples in heterotic and type II orientifolds in
which combined fluxes and condensates lead to vacua with small supersymmetry
breaking scale. We clarify the respective roles of fluxes and condensates in
supersymmetry breaking, and analyze the scaling properties of the gravitino
mass.Comment: 17 pages, C
Nearly K\"ahler heterotic compactifications with fermion condensates
We revisit AdS_4 heterotic compactifications on nearly K\"ahler manifolds in
the presence of H-flux and certain fermion condensates. Unlike previous
studies, we do not assume the vanishing of the supersymmetry variations.
Instead we determine the full equations of motion originating from the
ten-dimensional action, and subsequently we provide explicit solutions to them
on nearly K\"ahler manifolds at first order in alpha'. The Bianchi identity is
also taken into account in order to guarantee the absence of all anomalies. In
the presence of H-flux, which is identified with the torsion of the internal
space, as well as of fermion condensates in the gaugino and dilatino sectors,
new solutions are determined. These solutions provide a full classification of
consistent backgrounds of heterotic supergravity under our assumptions. All the
new solutions are non-supersymmetric, while previously known supersymmetric
ones are recovered too. Our results indicate that fully consistent
(supersymmetric or not) heterotic vacua on nearly K\"ahler manifolds are
scarce, even on AdS_4, and they can be completely classified.Comment: 1+17 pages, 1 figure; v2: remark and two references added, published
versio
Coset Space Dimensional Reduction and Wilson Flux Breaking of Ten-Dimensional N=1, E(8) Gauge Theory
We consider a N=1 supersymmetric E(8) gauge theory, defined in ten dimensions
and we determine all four-dimensional gauge theories resulting from the
generalized dimensional reduction a la Forgacs-Manton over coset spaces,
followed by a subsequent application of the Wilson flux spontaneous symmetry
breaking mechanism. Our investigation is constrained only by the requirements
that (i) the dimensional reduction leads to the potentially phenomenologically
interesting, anomaly free, four-dimensional E(6), SO(10) and SU(5) GUTs and
(ii) the Wilson flux mechanism makes use only of the freely acting discrete
symmetries of all possible six-dimensional coset spaces.Comment: 45 pages, 2 figures, 10 tables, uses xy.sty, longtable.sty,
ltxtable.sty, (a shorter version will be published in Eur. Phys. J. C
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