286 research outputs found
Proposals for Bottom Quark/Squark Renormalization in the Complex MSSM
We present a consistent renormalization of the top and bottom quark/squark
sector of the MSSM with complex parameters (cMSSM). Various renormalization
schemes are defined, analyzed analytically and tested numerically in the decays
Stop_2 -> Sbot_i H+/W+ (i = 1,2). No scheme is found that produces numerically
acceptable results over all the cMSSM parameter space, where problems occur
mostly already for real parameters. Two schemes are identified that show the
most robust behavior. A numerical analysis of the four partial stop decay
widths is performed in our "preferred" scheme, "m_b, A_b DRbar". The full
one-loop corrections to the corresponding partial decay widths are evaluated
including hard QED and QCD radiation. We find mostly modest corrections at the
one-loop level.Comment: 47 pages, 12 figure
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
Two-Loop Corrections to the Neutral Higgs Boson Masses in the CP-Violating NMSSM
We present our calculation of the two-loop corrections of to the neutral Higgs boson masses of the CP-violating
Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM). The
calculation is performed in the Feynman diagrammatic approach in the gaugeless
limit at vanishing external momentum. We apply a mixed
-on-shell (OS) renormalization scheme for the NMSSM
input parameters. Furthermore, we exploit a as well as
an OS renormalization in the top/stop sector. The corrections are implemented
in the Fortran code NMSSMCALC for the calculation of the Higgs spectrum both in
the CP-conserving and CP-violating NMSSM. The code also provides the Higgs
boson decays including the state-of-the-art higher-order corrections. The
corrections computed in this work improve the already available corrections in
NMSSMCALC which are the full one-loop corrections without any approximation and
the two-loop corrections in the gaugeless limit
and at vanishing external momentum. Depending on the chosen parameter point, we
find that the corrections add about
4-7% to the one-loop mass of the SM-like Higgs boson for
renormalization in the top/stop sector and they reduce
the mass by about 6-9% if OS renormalization is applied. For an estimate of the
theoretical uncertainty we vary the renormalization scale and change the
renormalization scheme and show that care has to be taken in the corresponding
interpretation
Higher-Order Corrected Higgs Bosons in FeynHiggs 2.5
Large higher-order corrections enter the Higgs boson sector of the MSSM via
Higgs-boson self-energies. Their effects have to be taken into account for the
correct treatment of loop-corrected Higgs-boson mass eigenstates as external
(on-shell) or internal particles in Feynman diagrams. We review how the loop
corrections, including momentum dependence and imaginary contributions, are
correctly taken into account for external (on-shell) Higgs boson and how
effective couplings can be derived. The proceedures are implemented in the code
FeynHiggs 2.5.Comment: 8 pages, no figures. Two talks given at the LCWS06 March 2006,
Bangalore, Indi
New Developments in FormCalc 8.4
We present new developments in FeynArts 3.9 and FormCalc 8.4, in particular
the MSSMCT model file including the complete one-loop renormalization,
vectorization/parallelization issues, and the interface to the Ninja library
for tensor reduction.Comment: 7 pages, proceedings contribution to Loops & Legs 2014, April 27-May
2, 2014, Weimar, German
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