609 research outputs found
Minimal Nonminimal Supersymmetric Standard Model
We review the basic field-theoretic and phenomenological features of the
recently introduced Minimal Nonminimal Supersymmetric Standard Model (MNSSM).
The introduced model is the simplest and most economic version among the
proposed nonminimal supersymmetric models, in which the so-called -problem
can be successfully addressed. As opposed to the MSSM and the
frequently-discussed NMSSM, the MNSSM can naturally predict the existence of a
light charged Higgs boson with a mass smaller than 100 GeV. Such a possible
realization of the Higgs sector can be soon be tested at the upgraded Run II
phase of the Tevatron collider.Comment: 8 pages, 4 figures, talk given at the conference ``Beyond the Desert
2002,'' 2--7 June 2002, Oulu, Finlan
CP-odd Neutral Higgs Effects in Top -- anti-Top Production
We study violation in the process at
an -TeV collider. As the source of violation we assume a two-Higgs
doublet model with an explicitly -noninvariant Higgs potential. Sizeable
-odd observables originating from the subprocess reaction, , may arise as a result of finite width effects of the neutral Higgs
particles. constraints due to final (initial) state interactions are also
taken into account. Numerical estimates of the asymmetry are given.Comment: 28 pages(2 Figs not included), LaTeX, MZ-TH/92-5
Thermal Right-Handed Sneutrino Dark Matter
We discuss the relic abundance of the right-handed sneutrinos in the
supersymmetric F_D-term model of hybrid inflation. As well as providing a
natural solution to the mu- and gravitino overabundance problems, the model
offers the lightest right-handed sneutrino as a candidate for thermal dark
matter. The F_D-term model predicts a new quartic coupling of purely
right-handed sneutrinos to the Higgs doublets that thermalizes the sneutrinos
and makes them annihilate sufficiently fast to a level compatible with the
current cosmic microwave background data. We discuss this scenario and identify
favourable regions of the parameter space within mSUGRA.Comment: Submitted for the SUSY08 proceedings, 3 pages, LaTeX, 2 eps figure
Higgs Sector Radiative Corrections and s-Channel Production
Higgs boson mass sum rules of supersymmetric models offer attractive targets
for precision tests at future muon colliders. These sum rules involve the gauge
boson masses as well as the masses of the Higgs boson states which can be
precisely measured in the -channel production process at a muon collider.
These measurements can sensitively probe radiative corrections to the Higgs
boson masses as well as test for CP-violation and nonminimality of the Higgs
sector.Comment: 4 pages, 2 figures, published versio
CP-Violating MSSM Higgs Bosons in the Light of LEP 2
In the MSSM, the CP parities of the neutral Higgs bosons may be mixed by
radiative effects induced by explicit CP violation in the third generation of
squarks. To allow for this possibility, we argue that the charged Higgs-boson
mass and tan(beta) should be used to parametrize the MSSM Higgs sector. We
introduce a new benchmark scenario of maximal CP violation appropriate for
direct searches of CP-violating MSSM Higgs bosons. We show that the bounds
established by LEP 2 on the MSSM Higgs sector may be substantially relaxed at
low and intermediate values of tan(beta) in the presence of CP violation, and
comment on possible Higgs boson signatures at LEP 2 within this framework.Comment: 16 pages, LaTeX, 4 encapsulated figure
Double beta decay and the extra-dimensional seesaw mechanism
We study the model-building conditions under which an observable 0vBB decay
signal is predicted due to Kaluza-Klein singlet neutrinos in theories with
large extra dimensions. Our analysis is based on 5-dimensional singlet-neutrino
models compactified on an S^1/Z_2 orbifold, where the Standard-Model fields are
localized on a 3-brane. We show that sizeable 0vBB rates within the above
minimal 5-dimensional framework would require a non-vanishing shift of the
3-brane from the orbifold fixed points by an amount smaller than the typical
scale 100 inverse MeV characterizing the Fermi nuclear momentum. The resulting
5-dimensional models predict a sizeable effective Majorana-neutrino mass that
could be several orders of magnitude larger than the light neutrino masses.Comment: 12 pages, 2 figures, talk presented by H. Paes at AHEP-2003,
Valencia, Spai
Renormalization-Group-Improved Effective Potential for the MSSM Higgs Sector with Explicit CP Violation
We perform a systematic study of the one-loop renormalization-group-improved
effective potential of the minimal supersymmetric extension of the Standard
Model (MSSM), including CP violation induced radiatively by soft trilinear
interactions related to squarks of the third generation. We calculate the
charged and neutral Higgs-boson masses and couplings, including the two-loop
logarithmic corrections that arise from QCD effects, as well as those
associated with the top- and bottom-quark Yukawa couplings. We also include the
potentially large two-loop non-logarithmic corrections induced by one-loop
threshold effects on the top- and bottom-quark Yukawa couplings, due to the
decoupling of the third-generation squarks. Within this minimal CP-violating
framework, the charged and neutral Higgs sectors become intimately related to
one another and therefore require a unified treatment. In the limit of a large
charged Higgs-boson mass, M_{H^+} >> M_Z, the lightest neutral Higgs boson
resembles that in the Standard Model (SM), and CP violation occurs only in the
heavy Higgs sector. Our analysis shows that sizeable radiative effects of CP
violation in the Higgs sector of the MSSM may lead to significant modifications
of previous studies for Higgs-boson searches at LEP2, the Tevatron and the LHC.
In particular, CP violation could enable a relatively light Higgs boson to
escape detection at LEP2.Comment: 55 pages, LaTeX, 9 eps figures, typo in (A.12) eliminate
On Gauge Invariance of Breit-Wigner Propagators
We present an approach to bosonic () as well as fermionic
(top-quark) Breit-Wigner propagators which is consistent with gauge invariance
arguments. In particular, for the -boson propagator we extend previous
analyses and show that the part proportional to must be
modified near the resonance. We derive a mass shift which agrees with results
obtained elsewhere by different methods. The modified form of a resonant heavy
fermion propagator is also given.Comment: 16 p., TeX, (final version
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