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Register a new userLikelihood analysis of the next-to-minimal supergravity motivated model
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In anticipation of data from the Large Hadron Collider (LHC) and the potential discovery of supersymmetry, in this work we seek an answer to the following: What are the chances that supersymmetry will be found at the LHC? Will the LHC data be enough to discover a given supersymmetric model? And what other measurements can assist the LHC establish the presence of supersymmetry? As a step toward answering these general questions, we calculate the odds of the next-to-minimal version of the popular supergravity motivated model (NmSuGra) being discovered at the LHC to be 4:3 (57 %). We also demonstrate that viable regions of the NmSuGra parameter space outside the LHC reach can be covered by upgrad
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Applying a likelihood analysis to the next-to-minimal supergravity-motivated model, we identify parameter space regions preferred by present experimental limits from collider, astrophysical, and low energy measurements. We then show that favored regions are amenable to detection by a combination of the CERN Large Hadron Collider and an upgraded Cryogenic Dark Matter Search, provided that the more than three sigma discrepancy in the difference of the experimental and the standard theoretical values of the anomalous magnetic moment of the muon prevails in the future.
We perform a likelihood analysis of the minimal Anomaly-Mediated Supersymmetry Breaking (mAMSB) model using constraints from cosmology and accelerator experiments. We find that a wino-like or a Higgsino-like neutralino LSP, $m_{tilde chi^0_{1}}$, may provide the cold dark matter (DM) with similar likelihood. The upper limit on the DM density from Planck and other experiments enforces $m_{tilde chi^0_{1}} lesssim 3~TeV$ after the inclusion of Sommerfeld enhancement in its annihilations. If most of the cold DM density is provided by the $tilde chi_0^1$, the measured value of the Higgs mass favours a limited range of $tan beta sim 5$ (or for $mu > 0$, $tan beta sim 45$) but the scalar mass $m_0$ is poorly constrained. In the wino-LSP case, $m_{3/2}$ is constrained to about $900~TeV$ and ${m_{tilde chi^0_{1}}}$ to $2.9pm0.1~TeV$, whereas in the Higgsino-LSP case $m_{3/2}$ has just a lower limit $gtrsim 650TeV$ ($gtrsim 480TeV$) and $m_{tilde chi^0_{1}}$ is constrained to $1.12 ~(1.13) pm0.02~TeV$ in the $mu>0$ ($mu<0$) scenario. In neither case can the anomalous magnetic moment of the muon, ${(g-2)_mu}$, be improved significantly relative to its Standard Model (SM) value, nor do flavour measurements constrain the model significantly, and there are poor prospects for discovering supersymmetric particles at the LHC, {though there} are some prospects for direct DM detection. On the other hand, if the ${m_{tilde chi^0_{1}}}$ contributes only a fraction of the cold DM density, {future LHC $E_T$-based searches for gluinos, squarks and heavier chargino and neutralino states as well as disappearing track searches in the wino-like LSP region will be relevant}, and interference effects enable ${rm BR}(B_{s, d} to mu^+mu^-)$ to agree with the data better than in the SM in the case of wino-like DM with $mu > 0$.
We consider the fully constrained version of the next-to-minimal supersymmetric extension of the standard model (cNMSSM) in which a singlet Higgs superfield is added to the two doublets that are present in the minimal extension (MSSM). Assuming universal boundary conditions at a high scale for the soft supersymmetry-breaking gaugino, sfermion and Higgs mass parameters as well as for the trilinear interactions, we find that the model is more constrained than the celebrated minimal supergravity model. The phenomenologically viable region in the parameter space of the cNMSSM corresponds to a small value for the universal scalar mass m_0: in this case, one single input parameter is sufficient to describe the phenomenology of the model once the available constraints from collider data and cosmology are imposed. We present the particle spectrum of this very predictive model and discuss how it can be distinguished from the MSSM.
We analyze the experimental data from the search for new particles at LEP 100 and obtain mass bounds for the neutralinos of the Next--To--Minimal Supersymmetric Standard Model (NMSSM). We find that for $tanbeta gsim 5.5$ a massless neutralino is still possible, while the lower mass bound for the second lightest neutralino corresponds approximately to that for the lightest neutralino in the Minimal Supersymmetric Standard Model (MSSM).
Within the framework of the Next-To-Minimal Supersymmetric Standard Model (NMSSM) we study neutralino production $e^+e^- longrightarrow tilde{chi}^0_i tilde{chi}^0_j$ ($i,j=1,ldots ,5$) at center-of-mass energies between 100 and 600 GeV and the decays of the heavier neutralinos into the LSP plus a fermion pair, a photon or a Higgs boson. For representative gaugino/higgsino mixing scenarios, where the light neutralinos have significant singlet components, we find some striking differences between the NMSSM and the minimal supersymmetric model. Since in the NMSSM neutralino and Higgs sector are strongly correlated, the decay of the second lightest neutralino into a Higgs boson and the LSP often is kinematically possible and even dominant in a large parameter region of typical NMSSM scenarios. Also, the decay rates into final states with a photon may be enhanced.
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