61 research outputs found
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 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 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
The LHC Higgs Boson Discovery: Implications for Finite Unified Theories
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. We confront the predictions of an SU(5) FUT with the top and
bottom quark masses and other low-energy experimental constraints, resulting in
a relatively heavy SUSY spectrum, naturally consistent with the non-observation
of those particles at the LHC. The light Higgs boson mass is automatically
predicted in the range compatible with the Higgs discovery at the LHC.
Requiring a light Higgs-boson mass in the precise range of M_h = 125.6 +- 2.1
GeV favors the lower part of the allowed spectrum, resulting in clear
predictions for the discovery potential at current and future pp, as well as
future e+e- colliders.Comment: 31 pages, 3 figures, review prepared for IJMP
Finite SU(3)^3 model
We consider N=1 supersymmetric gauge theories based on the group SU(N)_1 x
SU(N)_2 x ... x SU(N)_k with matter content (N,N*,1,...,1) + (1,N,N*,..., 1) +
>... + (N*,1,1,...,N) as candidates for the unification symmetry of all
particles. In particular we examine to which extent such theories can become
finite, and find that a necessary condition is that there should be exactly
three families. From phenomenological considerations an SU(3)^3 model is
singled out. We consider an all-loop and a two-loop finite model based on this
gauge group and we study their predictions concerning the third generation
quark masses.Comment: 4 pages, 2 figures. Talk given at 17th International Conference on
Supersymmetry and the Unification of Fundamental Interactions (SUSY09),
Boston, USA, 5-10 June 200
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.Comment: 16 pages, 4 figure
Selecting Finite Unified Theories with Current Data
Finite Unified Theories (FUTs) are N=1 supersymmetric Grand Unified Theories
that can be made all-loop finite, leading to a severe reduction of the free
parameters. We review the investigation of FUTs based on SU(5) in the context
of low-energy phenomenology observables. Using the restrictions from the top
and bottom quark masses, it is possible to 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
derive the predictions for the supersymmetric particle spectrum and the
prospects for discoveries at the LHC.Comment: 3 pages, 3 figures, talk given at SUSY08, Seoul, Kore
Four-dimensional heterotic strings and conformal field theory
The techniques of (super) conformal field theory are applied to 4-dimensional heterotic string theories. We discuss certain aspects of 4-dimensional strings in the framework of the bosonic lattice approach such as the realization of superconformal symmetry, character valued partition functions, construction of vertex operators and ghost picture changing. As an application we compute all possible 3- and 4-point tree amplitudes of the massless fields and derive from them the low energy effective action of the massless modes. Some effects for the massless spectrum due to one-loop string effects are also mentioned
The LHC Higgs Boson Discovery: Updated implications for Finite Unified Theories and the SUSY breaking scale
Finite Unified Theories (FUTs) are N = 1 supersymmetric Grand Unified
Theories which can be made finite to all orders in perturbation theory, based
on the principle of reduction of couplings. The latter consists in searching
for renormalization group invariant relations among parameters of a
renormalizable theory holding to all orders in perturbation theory. FUTs have
proven very successful so far. In particular, they predicted the top quark mass
one and half years before its experimental discovery, while around five years
before the Higgs boson discovery a particular FUT was predicting the light
Higgs boson in the mass range ~ 121 - 126 GeV, in striking agreement with the
discovery at LHC. Here we review the basic properties of the supersymmetric
theories and in particular finite theories resulting from the application of
the method of reduction of couplings in their dimensionless and dimensionful
sectors. Then we analyse the phenomenologically favoured FUT, based on SU(5).
This particular FUT leads to a finiteness constrained version of the MSSM,
which naturally predicts a relatively heavy spectrum with coloured
supersymmetric particles above 2.7 TeV, consistent with the non-observation of
those particles at the LHC. The electroweak supersymmetric spectrum starts
below 1 TeV and large parts of the allowed spectrum of the lighter might be
accessible at CLIC. The FCC-hh will be able to fully test the predicted
spectrum.Comment: 33 pages, 3 figures. arXiv admin note: substantial text overlap with
arXiv:1412.5766, arXiv:1305.5073, arXiv:1101.2476, arXiv:1001.0428,
arXiv:hep-ph/9703289, arXiv:hep-ph/9704218, arXiv:1712.0272
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