735 research outputs found
Singlino dominated LSP as CDM candidate in supersymmetric models with an extra U(1)
We consider a singlino dominated neutralino in supersymmetric models with an
extra U(1). In case both the term and also the mass are
generated by the vacuum expectation value of the scalar component of the same
singlet chiral superfield, generically the lightest neutralino is not expected
to be dominated by the singlino. However, if the gaugino corresponding to the
extra U(1) is sufficiently heavy, the lightest neutralino can be dominated by
the singlino and still satisfy the constraints resulting from the
phenomenology. We assume a supersymmetry breaking scenario in which the extra
U(1) gaugino can be much heavier than other gauginos. In that framework we show
that the singlino dominated lightest neutralino may be a good candidate for
dark matter in a parameter space where various phenomenological constraints are
satisfied.Comment: 25 pages, 6 figures, title is changed, introduction is extended,
sec.2 is moved to appendix, some references are added, published versio
D-term inflation and neutrino mass
We study a -term inflation scenario in a model extended from the minimal
supersymmetric standard model (MSSM) by two additional abelian factor groups
focussing on its particle physics aspects. Condensates of the fields related to
the inflation can naturally give a possible solution to both the -problem
in the MSSM and the neutrino mass through their nonrenormalizable couplings to
the MSSM fields. Mixings between neutrinos and neutralinos are also induced by
some of these condensates. Small neutrino masses are generated by a weak scale
seesaw mechanism as a result of these mixings. Moreover, the decay of the
condensates may be able to cause the leptogenesis. Usually known discrepancy
between both values of a Fayet-Iliopoulos -term which are predicted by the
COBE normalization and also by an anomalous U(1) in the weakly-coupled
superstring might be reconciled.Comment: 21 pages, LaTeX, small modifications, one reference adde
Radiative symmetry breaking and Higgs mass bound in the NMSSM
We study the upper mass bound of the lightest neutral Higgs scalar in the
NMSSM using the RGE analysis. We require the successful occurence of the
electroweak radiative symmetry breaking to restrict the parameter space. As a
result the upper mass bound is largely restricted compared with the
one estimated without imposing this condition. We point out some features of
related to the initial value of and discuss why the models with
more extra matters of SU(5) could bring the larger
maximum value of .Comment: 8 pages, latex, 4 eps-figure
SUSY breaking based on Abelian gaugino kinetic term mixings
We present a SUSY breaking scenario based on Abelian gaugino kinetic term
mixings between hidden and observable sectors. If an extra U(1) gaugino in the
observable sector obtains a large mass through this mixing effect based on SUSY
breaking in the hidden sector, soft SUSY breaking parameters in the MSSM may be
affected by radiative effects due to this gaugino mass. New phenomenological
aspects are discussed in such a SUSY breaking scenario.Comment: latex, 12pages, 2figures, published versio
Reconciliation of CDM abundance and in a radiative seesaw model
We reexamine relic abundance of a singlet fermion as a CDM candidate, which
contributes to the neutrino mass generation through radiative seesaw mechanism.
We search solutions for Yukawa couplings and the mass spectrum of relevant
fields to explain neutrino oscillation data. For such solutions, we show that
an abundance of a lightest singlet fermion can be consistent with WMAP data
without conflicting with both bounds of and . This reconciliation does not need any modification of the original
radiative seesaw model other than by specifying flavor structure of Yukawa
couplings and taking account of coannihilation effects.Comment: 16 pages, 2 figures, accepted version for publication
Gaugino CP phases and EDMs in the extended gauge mediation SUSY breaking
We study phenomenological aspects of the soft supersymmetry breaking
parameters in a model with the extended gauge mediation supersymmetry breaking.
In this model gaugino masses can be non-universal and as its result physical
CP-phases remain in the gaugino sector even after the R-transformation. These
phases contribute to the electric dipole moment (EDM) of an electron and a
neutron. We show that their experimental bounds can be satisfied even for the
situation such that there exist the order one CP-phases and the masses of
superpartners are of the order of 100 GeV.Comment: LaTeX, 26 pages, 6 figure
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