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

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

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 $Z_3$ 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 $300 {\rm fb}^{-1}$.Comment: 8 pages, 1 figure, to appear in the Proceedings of the Les Houches Workshop 2003: ``Physics at TeV Colliders'