1,055 research outputs found
MW and sin^2\theta_eff in Split SUSY: present and future expectations
We analyse the precision electroweak observables MW and sin^2\theta_eff and
their correlations in the recently proposed Split SUSY model. We compare the
results with the Standard Model and Minimal Supersymmetric Standard Model
predictions, and with present and future experimental accuracies. Present
experimental accuracies in (MW, sin^2\theta_eff) do not allow constraints to be
placed on the Split SUSY parameter space. We find that the shifts in (MW,
sin^2\theta_eff) induced by Split SUSY can be larger than the anticipated
accuracy of the GigaZ option of the International Linear Collider, and that the
most sensitive observable is sin^2\theta_eff. These large shifts are possible
also for large chargino masses in scenarios with small tan(\beta) =~ 1.Comment: LaTeX, 13 pages, 4 figures. Comments adde
Determination of Higgs-boson couplings at the LHC
We investigate the determination of Higgs boson couplings to gauge bosons and
fermions at the LHC from data on Higgs boson production and decay. We
demonstrate that very mild theoretical assumptions, which are valid in general
multi-Higgs doublet models, are sufficient to allow the extraction of absolute
values of the couplings rather than just ratios of the couplings. For Higgs
masses below 200 GeV we find accuracies of 10-40% for the Higgs couplings and
the total Higgs boson width after several years of LHC running. The sensitivity
of the Higgs coupling measurements to deviations from the Standard Model
predictions is studied for an MSSM scenario.Comment: 9 pages, contribution to the proceedings of the XXXIXth Rencontres de
Moriond, La Thuile, March 200
Novel Higgs decay signals in R-parity violating models
In supersymmetric models the lightest Higgs boson may decay with a sizable
branching ratio into a pair of light neutralinos. We analyze such decays within
the context of the minimal supersymmetric standard model with R-parity
violation, where the neutralino itself is unstable and decays into Standard
Model fermions. We show that the R-parity violating couplings induce novel
Higgs decay signals that might facilitate the discovery of the Higgs boson at
colliders. At the LHC, the Higgs may be observed, for instance, through its
decay -via two neutralinos- into final states containing missing energy and
isolated charged leptons such as , and .
Another promising possibility is the search for the displaced vertices
associated with the neutralino decay. We also point out that Higgs searches at
the LHC might additionally provide the first evidence of R-parity violation.Comment: 15 pages, 7 figures. Corrected affiliation
MSSM Higgs Bosons from Stop and Chargino Decays
The Higgs bosons of the MSSM can be produced from the decay of SUSY
particles. We review the evalulation of two decay modes in the MSSM with
complex parameters (cMSSM). The first type is the decay of the heavy scalar top
quark to a lighter scalar quark and a Higgs boson. The second type is the decay
of the heavy chargino to a lighter chargino/neutralino and a Higgs boson. The
evaluation is based on a full one-loop calculation including hard QED and QCD
radiation. We find sizable contributions to many partial decay widths and
branching ratios. They are roughly of O(10%) of the tree-level results, but can
go up to 30% or higher. These contributions are important for the correct
interpretation of scalar top quark decays at a future linear e+e- collider.Comment: 7 pages, 2 figures, talk given at the LCWS 2011, September 2011,
Granada, Spai
The Higgs Boson Production Cross Section as a Precision Observable?
We investigate what can be learned at a linear collider about the sector of
electroweak symmetry breaking from a precise measurement of the Higgs boson
production cross section through the process e+e- -> hZ. We focus on deviations
from the Standard Model arising in its minimal supersymmetric extension. The
analysis is performed within two realistic future scenarios, taking into
account all prospective experimental errors on supersymmetric particle masses
as well as uncertainties from unknown higher order corrections. We find that
information on tan beta and M_A could be obtained from a cross section
measurement with a precision of 0.5 - 1 %. Alternatively, information could be
obtained on the gaugino mass parameters M_2 and mu if they are relatively
small, M_2, mu approximately 200 GeV.Comment: 13 pages, 3 figures. Discussion on experimental errors enlarged,
references added and updated. Version to appear in Phys. Rev.
Precision Observables in the MSSM: W mass and the muon magnetic moment
The precision observables M_W and g-2 of the muon are discussed in the
framework of the MSSM. Recent progress in the evaluation of the theoretical
predictions is described, and the MSSM predictions are compared with the SM
predictions and the experimental values.Comment: 4 pages, 2 figures. To appear in Proceedings of SUSY06, the 14th
International Conference on Supersymmetry and the Unification of Fundamental
Interactions, UC Irvine, California, 12-17 June 200
Electroweak and supersymmetric two-loop corrections to (g-2)_\mu
We present the up to now most precise evaluation of electroweak and
supersymmetric contributions to the anomalous magnetic moment of the muon \amu,
describing in detail also the calculational techniques. We calculate the
bosonic two-loop contributions in the Standard Model without the approximation
of a heavy Higgs-boson mass, finding corrections up to 0.2*10^{-10} for a light
Higgs boson. In the Minimal Supersymmetric Standard Model the corresponding
two-loop contributions from the two-Higgs-doublet model part differ from the
Standard Model result by up to 0.3*10^{-10}. Finally, we evaluate the diagrams
where a loop of charginos or neutralinos, the superpartners of gauge and Higgs
bosons, is inserted into a two-Higgs-doublet one-loop diagram. These
corrections can amount up to 10*10^{-10}, which is almost 2\sigma of the
current experimental uncertainty.Comment: 23 pages, 9 figure
Self-interactions of the lightest MSSM Higgs boson in the large pseudoscalar-mass limit
We investigate the decoupling properties of the Higgs-sector-induced one-loop
corrections in the lightest Higgs-boson self-couplings, in the framework of the
Minimal Supersymmetric Standard Model (MSSM). The renormalized n-point vertex
functions with external Higgs particles in the MSSM and in the SM are derived
to the one-loop level and compared in the MA >> MZ limit. The computation has
been done in a general R_{xi} gauge and the on-shell renormalization scheme is
chosen. By a comparison of the renormalized lightest Higgs-boson h^0 vertex
functions with respect to the corresponding SM ones, we find that the
differences between the predictions of both models are summarized in the
lightest Higgs-boson mass correction Delta Mh. Consequently, the radiative
corrections are absorbed in the Higgs-boson mass, and the trilinear and quartic
h^0 self-couplings acquire the same structure as the couplings of the SM
Higgs-boson. Therefore, decoupling of the heavy MSSM Higgs bosons occurs and
the MSSM h^0 self-interactions converge to the SM ones in the MA >> MZ limit.Comment: LaTeX, 26 pages, 1 figure. Sections 4 and 5 summarized in one
section. Some references added. Published version in Phys. Rev.
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