Realistic predictions for the detection of supersymmetric dark matter

We present new predictions for the detection of supersymmetric dark matter via its annihilation in the Sun and elastic scattering off heavy nuclei in the laboratory. Our predictions include many effects found in realistic models such as non-degenerate left- and right-squark masses, unequal supersymmetric Higgs v.e.v.s and photino/higgsino/zino mixing in the lightest supersymmetric particle (LSP). Hadronic matrix elements are estimated using either the naive quark model or the EMC measurement of the spin-dependent proton structure function and perturbative QCD. Nuclear matrix elements are calculated using the shell-model and the small effects of quark vector current operators are discussed. Previous predictions for the elastic LSP-proton scattering cross section, and hence for high energy solar neutrinos from LSP annihilations, are reduced by the EMC estimate and by unequal squark masses, but may be increased by unequal Higgs v.e.v.s. Previous predictions for elastic photino scattering off nuclei with unpaired neutrons are greatly enhanced by the EMC estimate. As a result, preferences for the nuclei to be used in laboratory experiments to detect supersymmetric dark matter may be greatly altered.     

Implications of muon anomalous magnetic moment for supersymmetric dark matter

The anomalous magnetic moment of the muon has recently been measured to be in conflict with the standard model prediction with an excess of 2.6sigma. Taking the excess at face value as a measurement of the supersymmetric contribution, we find that at 95% confidence level it imposes an upper bound of 500 GeV on the neutralino mass and forbids Higgsinos as being the bulk of cold dark matter. Other implications for the astrophysical detection of neutralinos include an accessible minimum direct detection rate, lower bounds on the indirect detection rate of neutrinos from the Sun and the Earth, and a suppression of the intensity of gamma ray lines from neutralino annihilations in the galactic halo.     

WMAP data and recent developments in supersymmetric dark matter

A brief review is given of the recent developments in the analyses of supersymmetric dark matter. Chief among these is the very accurate determination of the amount of cold dark matter in the universe from analyses using WMAP data. The implications of this data for the mSUGRA parameter space are analyzed. It is shown that the data admits solutions on the hyperbolic branch of the radiative breaking of the electroweak symmetry. A part of the hyperbolic branch lies in the so-called inversion region, where the LSP neutralino χ ₁ ⁰ becomes essentially a pure Higgsino and degenerates with the next-to-the-lightest neutralino χ ₂ ⁰ and the light chargino χ ₁ ^± . Thus, some of the conventional signals for the observation of supersymmetry in colliders (e.g., the missing energy signals) do not operate in this region. On the other hand, the inversion region contains a high degree of degeneracy of χ ₁ ⁰ , χ ₂ ⁰ , χ ₁ ^± leading to coannihilations, which allow for the satisfaction of the WMAP relic density constraints deep on the hyperbolic branch. Further, an analysis of the neutralino-proton cross sections in this region reveals that this region can still be accessible to dark matter experiments in the future. Constraints from g_π?2 and from B _s ⁰ → μ⁺μ^? are discussed. Future prospects are also discussed.     

Implications of collider experiments for detecting cold dark matter

By investigating the space of parameters of the minimal supersymmetric extension of the Standard Model, it is shown that an observation of at least one supersymmetric particle in high-energy experiments would increase considerably the importance of highly sensitive low-energy experiments aimed at detecting cold-dark-matter particles assumed to be neutralinos, the lightest supersymmetric particles, which are stable. On the other hand, nonobservation of direct signals from dark matter in such experiments can have a pronounced effect on the strategy of high-energy searches for the light charged Higgs boson.     

Implications of direct dark matter constraints for minimal supersymmetric standard model Higgs boson searches at the Tevatron

In regions of large tanbeta and small mAlpha, searches for heavy neutral minimal supersymmetric standard model (MSSM) Higgs bosons at the Tevatron are promising. At the same time, rates in direct dark matter experiments, such as CDMS, are enhanced in the case of large tanbeta and small mAlpha. As a result, there is a natural interplay between the heavy, neutral Higgs searches at the Tevatron and the region of parameter space explored by CDMS. We show that if the lightest neutralino makes up the dark matter of our universe, current limits from CDMS strongly constrain the prospects of heavy, neutral MSSM Higgs discovery at the Tevatron unless |mu| greater or approximately 400 GeV. The limits of CDMS projected for 2007 will increase this constraint to |mu| greater or approximately 800 GeV. If CDMS does observe neutralinos in the near future, however, it will make the discovery of Higgs bosons at the Tevatron far more likely.     

Cryogenic phonon-detector model with solid argon for detecting dark matter

Over the past few years, phonon detectors have emerged as a prevailing technology for detecting lowmass dark matter due to their low thresholds and high resolution. These detectors, which employ either dual-phase detectors combining phonon-light or phonon-electron interactions, have significantly advanced direct dark matter detection efforts. Argon, as a low-background and high-reserve detection medium, has also played a crucial role in this field. Both liquid-argon single-phase detectors and ga...     

Sleptons at post-WMAP benchmark points at LHC (CMS)

We study the possibility of detecting sleptons at post-WMAP benchmark points at LHC (CMS). We find that, at L_tot = 30 fb^?1, it would be possible to detect sleptons at points B, C, D, G. We also investigate the production and decays of right and left sleptons separately. We find that, at L_tot = 30 fb^?1, it would be possible to detect right sleptons with a mass up to 200 GeV and left ones with a mass up to 300 GeV.     

Inelastic dark matter at the LHC

The dark matter sector may be more complicated than anticipated. An inelastically scattering dark matter with a mass splitting above one MeV will make direct detection experiments hopeless, and render LHC the primary chance for discovery. We perform a model-independent study of inelastic dark matter at the LHC, concentrating on the parameter space with the mass splitting between the excited and ground states of dark matter above a few hundred MeV. The generic signatures of inelastic dark matter at the LHC are displaced pions together with a monojet plus missing energy, and can be tested at the 7 TeV LHC.     

Solar neutrinos: probing the quasi-isothermal solar core produced by supersymmetric dark matter particles

SNO measurements strongly constrain the central temperature of the Sun, to within a precision of much less than 1%. This result can be used to probe the parameter space of supersymmetric dark matter. In this first analysis we find a lower limit for the weakly interacting massive particle (WIMP) mass of 60 GeV. Furthermore, in the event that WIMPs create a quasi-isothermal core, they will produce a peculiar distribution of the solar neutrino fluxes measured on Earth. Typically, a WIMP with a mass of 100 GeV and annihilation cross section of 10(-34) cm(3)/sec will decrease the neutrino predictions, by up to 4% for the Cl, by 3% for the heavy water, and by 1% for the Ga detectors.     

Difficulty of detecting minihalos via gamma rays from dark matter annihilation

Analytical calculations and recent numerical experiments have shown that a sizable amount of the mass of our Galaxy is in a form of clumpy, virialized substructures that, according to Diemand et al., can be as light as 10(-6)M(.). In this work we estimate the gamma-ray flux expected from dark matter annihilation occurring within these minihalos, under the hypothesis that the bulk of dark matter is composed by neutralinos. We generate mock sky maps showing the angular distribution of the expected gamma-ray signal. We compare them with the sensitivities of satellite-borne experiments such as GLAST and find that a possible detection of minihalos is indeed very challenging.     

Model for cold dark matter

We present a model for cold dark matter based upon continuum bound states of thee ⁺ e ^– system. These continuum bound states, referred to as photonium states to distinguish them from the well-known bound states of positronium, are shown to have cross sections and lifetime properties consistent with abundant production in the early universe and survival to the present time. Thus photonium can easily account for more than 90% of the total mass of the universe.The authors have benefitted from discussions with Charles J. Benesh. This work was supported in part by the US DOE grant no. DE-FG02-87ER40371, Division of High Energy and Nuclear Physics and by contract no. W-7405-ENG-82.     

Indirect searches for dark matter

The current status of indirect searches for dark matter has been reviewed in a schematic way here. The main relevant experimental results of the recent years have been listed and the excitements and disappointments that their phenomenological interpretations in terms of almost-standard annihilating dark matter have brought along have been discussed. The main sources of uncertainties that affect this kind of searches are also listed. [Report number: Saclay T11/206, CERN-PH-TH/2011-257, extended version in arXiv:1202.1454], [Prepared for the Proceedings of Lepton?CPhoton 2011, Mumbai, India, 22?C27 Aug. 2011].