67 research outputs found
Masses and Couplings of the Lightest Higgs Bosons in the (M+1)SSM
We study the upper limits on the mass of the lightest and second lightest CP
even Higgs bosons in the (M+1)SSM, the MSSM extended by a gauge singlet. The
dominant two loop contributions to the effective potential are included, which
reduce the Higgs masses by 10 GeV. Since the coupling R of the lightest Higgs
scalar to gauge bosons can be small, we study in detail the relations between
the masses and couplings of both lightest scalars. We present upper bounds on
the mass of a 'strongly' coupled Higgs (R > 1/2) as a function of lower
experimental limits on the mass of a 'weakly' coupled Higgs (R < 1/2). With the
help of these results, the whole parameter space of the model can be covered by
Higgs boson searches.Comment: Changed notation and added explanations; to appear in European
Journal of Physics
Neutralino Cascades in the (M+1)SSM
In the (M+1)SSM an additional gauge singlet Weyl spinor appears in the
neutralino sector. For a large part of the parameter space this approximative
eigenstate is the true LSP. Then most sparticle decays proceed via an
additional cascade involving the NLSP -> LSP transition, where the NLSP is the
non-singlet next-to-lightest neutralino. We present a comprehensive list of all
processes, which contribute to the NLSP -> LSP transition, the partial widths
and the total NLSP decay rate. We perform a scan of the parameters of the model
compatible with universal soft terms, and find that the NLSP life time can be
quite large, leading to macroscopically displaced vertices. Our results imply
that the signatures for sparticle production in the (M+1)SSM can be very
different from the MSSM, and are important for calculations of the abundance of
dark matter in this model.Comment: 25 pages (LaTeX2e), 8 figs., explanations adde
Topologies of the (M+1)SSM with a Singlino LSP at LEP2
We study the possible signals of the (M+1)SSM with a singlino LSP at LEP2.
First we identify regions of the parameter space which are ruled out by
negative results of sparticle searches in the context of the MSSM. In the
remaining kinematically accessible regions we present total event rates for
topologies which require further studies, i.e. estimations of the corresponding
efficiencies: various 4 charged fermion final states with missing energy,
possibly with displaced vertices due to a long lifetime of the NLSP, the second
lightest neutralino. Searches for these unconventional signatures are essential
in order to cover the entire kinematically accessible parameter space of the
(M+1)SSM with a singlino LSP at LEP2.Comment: 21 pages (LaTeX2e), 2 figs., table with all possible final states
adde
NMSSM Higgs Discovery at the LHC
We demonstrate that Higgs discovery at the LHC is possible in the context of
the NMSSM even for those scenarios such that the only strongly produced Higgs
boson is a very SM-like CP-even scalar which decays almost entirely to a pair
of relatvely light CP-odd states. In combination with other search channels, we
are on the verge of demonstrating that detection of at least one of the NMSSM
Higgs bosons is guaranteed at the LHC for accumulated luminosity of .Comment: 8 pages, 1 figure, to appear in the Proceedings of the Les Houches
Workshop 2003: ``Physics at TeV Colliders'
Reinforcing the no-lose theorem for NMSSM Higgs discovery at the LHC
We show the potential of the LHC to detect a CP-even Higgs boson of the
NMSSM, or , decaying into two rather light CP-odd Higgs bosons,
, by exploiting the production mode based on Higgs-strahlung off
-quarks, i.e., the channel . We also consider the
case of decays. It is found that these decays have dominant
BRs over large regions of the NMSSM parameter space where tan is large,
a condition which also favours the production rates.
Further decays of the light Higgs boson pairs ( and ) into photon,
muon, tau and final states are also considered. The overall production and
decay rates for these processes at inclusive level are sizable and should help
extracting at least one Higgs boson signal over the NMSSM parameter space.Comment: 19 pages, 9 figures, added comments and corrected typo
Relic density of dark matter in the NMSSM
We present a code to compute the relic density of dark matter in the
Next-to-Minimal Supersymmetric Standard Model (NMSSM). Dominant corrections to
the Higgs masses are calculated with NMHDECAY as well as theoretical and
collider constraints. All neutralino annihilation and coannihilation processes
are then computed with an extended version of micrOMEGAs, taking into acount
higher order corrections to Higgs vertices. We explore the parameter space of
the NMSSM and consider in particular the case of a bino LSP, of a mixed
bino-higgsino LSP and of a singlino LSP. As compared to the MSSM, neutralino
annihilation is often more efficient as it can take place via (additional)
Higgs resonances as well as annihilation into light Higgs states. Models with a
large singlino component can be compatible with WMAP constraints.Comment: 25 pages, 8 figures; one reference added and minor change in
acknowledgement
Dark Matter in a Constrained NMSSM
We explore the parameter space of a Constrained Next-to-Minimal
Supersymmetric Standard Model with GUT scale boundary conditions (CNMSSM) and
find regions where the relic density of the lightest neutralino is compatible
with the WMAP measurement. We emphasize differences with the MSSM: cases where
annihilation of the LSP occurs via a Higgs resonance at low values of tan\beta
and cases where the LSP has a large singlino component. The particle spectrum
as well as theoretical and collider constraints are calculated with NMSSMTools.
All neutralino annihilation and coannihilation processes are then computed with
micrOMEGAs, taking into account higher order corrections to the Higgs sector.Comment: 17 pages, 6 figures, references added, some comments added, version
to be published in JCA
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