113 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
Higgs Sector of Non-minimal Supersymmetric Models at Future Hadron Colliders
We investigate the potential of current and planned hadron colliders
operating at the TeV scale in disentangling the structure of the Higgs sector
of non-minimal Supersymmetric extensions of the Standard Model with an extra
gauge singlet. We assume universality of the soft Supersymmetry breaking terms
at the GUT scale as well as a CP-even Higgs boson with mass around 115 GeV, as
suggested by LEP. We find that mixing angles between the doublet and singlet
Higgs states are always small. However, concrete prospects exist at both the
Tevatron (Run II) and the Large Hadron Collider of detecting at least one
neutral Higgs state with a dominant singlet component, in addition to those
available from a doublet Higgs sector which is similar to the one of the
Minimal Supersymmetric Standard Model.Comment: 4 pages, 2 figures, latex, contribution to the APS/DPF/DPB Summer
Study on the `Future of Particle Physics (Snowmass 2001)', Snowmass,
Colorado, 30 June - 21 July 200
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
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
Precision measurements, dark matter direct detection and LHC Higgs searches in a constrained NMSSM
We reexamine the constrained version of the Next-to-Minimal Supersymmetric
Standard Model with semi universal parameters at the GUT scale (CNMSSM). We
include constraints from collider searches for Higgs and SUSY particles, upper
bound on the relic density of dark matter, measurements of the muon anomalous
magnetic moment and of B-physics observables as well as direct searches for
dark matter. We then study the prospects for direct detection of dark matter in
large scale detectors and comment on the prospects for discovery of heavy Higgs
states at the LHC.Comment: 22 pages, 8 figures. Note added and references adde
Charge Breaking Minima in the Broken R-parity Minimal Supersymmetric Standard Model
We reconsider the possible presence of charge and colour breaking minima in
the scalar potential of the minimal supersymmetric standard model (MSSM) and
its minimal generalization with R-parity explicitly broken by bilinear terms
(RMSSM). First we generalize some results previously derived for the MSSM case.
Next we investigate how robust is the MSSM against its RMSSM extension. We
examine the constraints on the RMSSM parameter space that follow from the
required absence of charge breaking minima in the scalar potential. We point
out the possibility of generating non--zero vacuum expectation values for the
charged Higgs field which is not present in the MSSM. However, given the
smallness of neutrino masses indicated by neutrino oscillation data, we show
that the RMSSM represents only a slight perturbation of the MSSM and is thus as
safe (or unsafe) as the MSSM itself from unwanted minima in the scalar
potential.Comment: Latex 16 pages, 2 figure
Status and prospects of the nMSSM after LHC Run-1
The new minimal supersymmetric standard model (nMSSM), a variant of the
general next to minimal supersymmetric standard model (NMSSM) without
symmetry, features a naturally light singlino with a mass below 75 GeV. In
light of the new constraints from LHC Run-1 on the Higgs couplings, sparticles
searches and flavour observables, we define the parameter space of the model
which is compatible with both collider and dark matter (DM) properties. Among
the regions compatible with these constraints, implemented through NMSSMTools,
SModelS and MadAnalysis 5, only one with a singlino lightest supersymmetric
particle (LSP) with a mass around 5 GeV can explain all the DM abundance of the
universe, while heavier mixed singlinos can only form one of the DM components.
Typical collider signatures for each region of the parameter space are
investigated. In particular, the decay of the 125 GeV Higgs into light scalars
and/or pseudoscalars and the decay of the heavy Higgs into charginos and
neutralinos, provide distinctive signatures of the model. Moreover, the
sfermion decays usually proceed through heavier neutralinos rather than
directly into the LSP, as the couplings to the singlino are suppressed. We also
show that direct detection searches are complementary to collider ones, and
that a future ton-scale detector could completely probe the region of parameter
space with a LSP mass around 65 GeV.Comment: 33 pages, 9 figures. Version accepted for publication in JHE
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'
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