1,395 research outputs found
The MSSM in the Light of Precision Data
The potential of present and anticipated future electroweak precision data,
including the Higgs boson and top quark masses, for testing quantum effects of
the electroweak theory is investigated in the context of the Minimal
Supersymmetric Standard Model (MSSM). The present status of the theoretical
predictions is analyzed. The impact of the parametric uncertainties from the
experimental errors of the input parameters is studied, and an estimate for the
remaining uncertainties from unknown higher-order corrections is given both in
the Standard Model (SM) and the MSSM. Examples of electroweak precision tests
in the mSUGRA scenario and the unconstrained MSSM are analyzed, and the status
of the global fit to all data is discussed.Comment: 16 pages, 4 figures, to appear in the proceedings of the workshop
``Electroweak precision data and the Higgs mass'', DESY Zeuthen, February
200
Electroweak Precision Tests with GigaZ
By running the prospective high-energy e^+e^- collider TESLA in the GigaZ
mode on the Z resonance, experiments can be performed on the basis of more than
10^9 Z events. This will allow the measurement of the effective electroweak
mixing angle to an accuracy of \delta sin^2(theta_W,eff) \approx \pm 10^-5. The
W boson mass is likewise expected to be measurable with an error of \delta M_W
\approx \pm 6 MeV near the W^+W^ threshold. We review the electroweak precision
tests that can be performed with these high precision measurements within the
Standard Model (SM) and its minimal Supersymmetric extension (MSSM). The
complementarity of direct measurements at a prospective linear e^+e^- collider
and indirect constraints following from measurements performed at GigaZ is
emphasized.Comment: 5 pages, 3 figures, talk given by S. Heinemeyer at the 5th
International Linear Collider Workshop (LCWS 2000), Fermilab, Batavia,
Illinois, 24-28 Oct 200
Higgs Production and Decay in the MSSM: Status and Perspectives
The theoretical predictions in the MSSM for Higgs-boson production at a
future e^+e^- Linear Collider and Higgs-boson decay processes are discussed
focusing in particular on recent diagrammatic two-loop results in the MSSM
Higgs sector. The present status of the theoretical predictions is briefly
summarized, and it is emphasized that considerable improvements will be
necessary in order to match the high experimental accuracy achievable at a
future Linear Collider.Comment: 6 pages, 2 figures, to appear in the proceedings of LCWS 200
Higher-order results in the Higgs sector of the MSSM
We analyze the impact of the recent Feynman-diagrammatic (FD) two-loop
results for the mass of the lightest CP-even Higgs boson in the MSSM on the
theoretical upper bound for mh as a function of tan(beta). The results are
compared with previous results obtained by renormalization group (RG) methods.
The incorporation of dominant FD two-loop corrections into the decay width
\Gamma(h -> f \bar f) is also discussed.Comment: 4 pages, 2 figures, presented by G. Weiglein at the ``International
Europhysics Conference on High Energy Physics'', Tampere, July 199
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 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
FeynHiggsFast: a program for a fast calculation of masses and mixing angles in the Higgs Sector of the MSSM
FeynHiggsFast is a Fortran code for the calculation of the masses and the
mixing angle of the neutral CP-even Higgs bosons in the MSSM up to two-loop
order. It is based on a compact analytical approximation formula of the
complete diagrammatic one-loop and the dominant two-loop contributions. At the
one-loop level a leading logarithmic result is used, taking into account all
sectors of the MSSM. At the two-loop level at O(alpha alpha_s) the leading
logarithmic and non-logarithmic contributions are taken into account. The
approximation formula is valid for arbitrary choices of the parameters in the
Higgs sector of the model. Comparing its quality to the full diagrammatic
result, we find agreement better than 2 GeV for most parts of the MSSM
parameter space.Comment: 10 pages, 6 figures. Extended version of the contribution to the
Report of the HIGGS working group for the Workshop ``Physics at TeV
Colliders'' Les Houches, France, June 199
Implications of Results from Z- and WW-Threshold Running
One year of Z- and WW-Threshold running of TESLA can provide the possibility
to measure electroweak precision observables to an extremely high accuracy. At
the Z peak O(10^9) Z bosons and about 6 10^8 b quarks can be collected. We
employ the expected uncertainties \Delta MW = 6 MeV and \Delta sin(theta_W,eff)
= 0.00001 and demonstrate in this way that very stringent consistency tests of
the Standard Model and the Minimal Supersymmetric Standard Model will be
possible. The indirect determination of the Higgs-boson mass within the
Standard Model can reach an accuracy of about 5 %. The 6 10^8 b quarks can be
used to investigate various b physics topics.Comment: 7 pages, 2 figures, talk given at LCWS99, Sitges, Spain. Two
clarifications, one reference adde
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