Neutralino mass bounds at the upgraded LEP collider

We derive the allowed ranges of the spin--independent interaction cross section $\sigsip$ for the elastic scattering of neutralinos on proton for wide ranges of parameters of the general Minimal Supersymmetric Standard Model. We investigate the effects of the lower limits on Higgs and superpartner masses from colliders, as well as the impact of constraints from $\bsgamma$ and the new measurement of $\gmtwo$ on the upper and lower limits on $\sigsip$. We further explore the im...

In the minimal supersymmetric standard models, neutralino dark matter with mass of $m_{\chi}\sim m_Z/2\sim 45$ GeV and $m_{\chi}\sim m_h/2\sim 62$ GeV can have the thermal relic abundance $\Omega_{\chi_1}h^2\simeq 0.120$ via the $Z$- and Higgs-resonant annihilations, respectively, while avoiding all the current constraints. Phenomenology of such scenarios is determined only by three parameters, Bino mass $M_1$, Higgsino mass $\mu$, and $\tan\beta$, in the limit that all other...

The electroweak (EW) sector of the Minimal Supersymmetric Standard Model (MSSM) can account for a variety of experimental data. The lighest supersymmetric particle (LSP), which we take as the lightest neutralino, $\tilde \chi_1^0$, can account for the observed Dark Matter (DM) content of the universe via coannihilation with the next-to-LSP (NLSP), while being in agreement with negative results from Direct Detection (DD) experiments. Owing to relatively small production cross-...

We revisit the current LHC constraints on the electroweak-ino sector parameters in the minimal supersymmetric standard model (MSSM) that are relevant to explaining the $(g-2)_\mu$ anomaly via the dominant chargino and muon sneutrino loop. Since the LHC bounds on electroweak-inos become weaker if they decay via an intermediate stau or a tau sneutrino instead of the first two generation sleptons, we perform a detailed analysis of the scenario with a bino as the lightest supersy...

It is one of the most challenging tasks at the Large Hadron Collider and at a future Linear Collider not only to observe physics beyond the Standard Model, but to clearly identify the underlying new physics model. In this paper we concentrate on the distinction between two different supersymmetric models, the MSSM and the NMSSM, as they can lead to similar low energy spectra. The NMSSM adds a singlet superfield to the MSSM particle spectrum and simplifies embedding a SM-like ...

We study the muon $(g-2)_{\mu}$ anomaly in light of neutralino dark matter and the LHC. We scan the MSSM parameters relevant to $(g-2)_{\mu}$ and focus on three distinct cases with different neutralino compositions. We find that the 2$\sigma$ range of $(g-2)_{\mu}$ requires the smuon ($\tilde{\mu}_1$) to be lighter than $\sim$ 500 (1000) GeV for $\tan \beta=10\,(50)$. Correspondingly the two lightest neutralinos, $\tilde{\chi}_{1}^0, \tilde{\chi}_{2}^0$, have to be lighter th...

We discuss the scenario of light neutralino dark matter in the minimal supersymmetric standard model, which is motivated by the results of some of the direct detection experiments --- DAMA, CoGENT, and CRESST. We update our previous analysis with the latest results of the LHC. We show that new LHC constraints disfavour the parameter region that can reproduce the results of DAMA and CoGENT.

The negative outcome of searches for supersymmetry performed at LEP have been used to derive indirect constraints on the parameters of the most plausible supersymmetric candidates for cold dark matter, in particular for the lightest neutralino. We review the basic ideas leading to the present lower limit on the lightest neutralino mass of about 37 GeV, with emphasis on the underlying assumptions.

Motivated by the recent measurement of muon anomalous magnetic moment at Fermilab, the rapid progress of the LHC search for supersymmetry, and the significantly improved sensitivities of dark matter direct detection experiments, we studied their impacts on the Minimal Supersymmetric Standard Model (MSSM). We conclude that higgsino mass should be larger than about $500~{\rm GeV}$ for $M_1 < 0 $ and $630~{\rm GeV}$ for $M_1 > 100~{\rm GeV}$, where $M_1$ denotes the bino mass. T...

We demonstrate that the lightest chargino can be lighter than the lightest neutralino in supersymmetric models with Dirac gaugino masses as well as within a curious parameter region of the MSSM. Given also a light gravitino, such as from low scale supersymmetry breaking, this mass hierarchy leads to an unusual signal where every superpartner cascades down to a chargino that decays into an on-shell W and a gravitino, possibly with a macroscopic chargino track. We clearly ident...