1,958 research outputs found

    New results from DAMA/LIBRA

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    DAMA/LIBRA is running at the Gran Sasso National Laboratory of the I.N.F.N.. Here the results obtained with a further exposure of 0.34 ton x yr are presented. They refer to two further annual cycles collected one before and one after the first DAMA/LIBRA upgrade occurred on September/October 2008. The cumulative exposure with those previously released by the former DAMA/NaI and by DAMA/LIBRA is now 1.17 ton x yr, corresponding to 13 annual cycles. The data further confirm the model independent evidence of the presence of Dark Matter (DM) particles in the galactic halo on the basis of the DM annual modulation signature (8.9 sigma C.L. for the cumulative exposure). In particular, with the cumulative exposure the modulation amplitude of the single-hit events in the (2 -- 6) keV energy interval measured in NaI(Tl) target is (0.0116 +- 0.0013) cpd/kg/keV; the measured phase is (146 +- 7) days and the measured period is (0.999 +- 0.002) yr, values well in agreement with those expected for the DM particles.Comment: presented at the Int. Conf. Beyond the Standard Models of Particle Physics, Cosmology and Astrophysics (BEYOND 2010), 1-6 February 2010, Cape Town, South Afric

    Dark Matter candidate in a Heavy Higgs Model - Direct Detection Rates

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    We investigate direct detection rates for Dark Matter candidates arise in a SU(2)LĂ—U(1)YSU(2)_L\times U(1)_Y with an additional doublet Higgs proposed by Barbieri, Hall and Rychkov. We refer this model as `Heavy Higgs Model'. The Standard Model Higgs mass comes out in this model very heavy adopting the few per cent chance that there is no Higgs boson mass below 200 GeV. The additional Higgs boson develops neither any VEV due to the choice of coefficient of the scalar potential of the model nor it has any coupling with fermions due to the incorporation of a discrete parity symmetry. Thus, the neutral components of the extra doublet are stable and can be considered as probable candidate of Cold Dark Matter. We have made calculations for three different types of Dark Matter experiments, namely, 76^{76}Ge (like GENIUS), DAMA (NaI) and XENON (131^{131}Xe). Also demonstrated the annual variation of Dark Matter detection in case of all three detectors considered.Comment: 10 pages, 9 figures, figures unchanged, text modified, version to appear in Mod. Phys. Lett.

    Relevance of the CDMSII events for mirror dark matter

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    Mirror dark matter offers a framework to explain the existing dark matter direct detection experiments, including the impressive DAMA annual modulation signal. Here we examine the implications of mirror dark matter for experiments like CDMSII/Ge and XENON10 which feature higher recoil energy threshold than the DAMA NaI experiments. We show that the two events seen in the CDMSII/Ge experiment are consistent with the interactions of the anticipated heavy ∼Fe′\sim Fe' component. This interpretation of the CDMSII/Ge events is a natural one given that a) mirror dark matter predicts an event rate which is sharply falling with respect to recoil energy and b) that the two observed events are in the low energy region near threshold. Importantly this interpretation of the CDMSII events can be checked by on-going and future experiments, and we hereby predict that the bulk of the events will be in the ER∼<18E_R \stackrel{<}{\sim} 18 keV region.Comment: about 7 page

    Implications of the DAMA/NaI and CDMS experiments for mirror matter-type dark matter

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    We re-analyse the implications of the DAMA/NaI experiment for mirror matter-type dark matter, taking into account information from the energy dependence of the DAMA annual modulation signal. This is combined with the null results from the CDMS experiment, leading to fairly well defined allowed regions of parameter space. The allowed regions of parameter space will be probed in the near future by the DAMA/LIBRA, CDMS, and other experiments, which should either exclude or confirm this explanation of the DAMA/NaI annual modulation signal. In particular, we predict that the CDMS experiments should find a positive signal around the threshold recoil energy region, E_R < 15 keV in the near future.Comment: about 15 pages, Some changes to the tex

    Technical aspects in dark matter investigations

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    Some theoretical and experimental aspects regarding the direct dark matter field are mentioned. In particular some arguments, which play a relevant role in the evaluation of model dependent interpretations of experimental results and in comparisons, are shortly addressed.Comment: Proceedings of TAUP 2011 Conferenc

    WIMPless dark matter and the excess gamma rays from the Galactic center

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    In this paper we discuss the excess gamma rays from the Galactic center, the WMAP haze and the CoGeNT and DAMA results in WIMPless models. At the same time we also investigate the low energy constraints from the anomalous magnetic moment of leptons and from some lepton flavor violating decays. It is found that, for scalar or vector WIMPless dark matter, neither the WMAP haze nor the CoGeNT and DAMA observations could be explained simultaneously with the excess gamma rays from the Galactic center. As to fermion WIMPless dark matter, it is only marginally possible to accommodate the CoGeNT and DAMA results with the excess gamma rays from the Galactic center with vector connector fields. On the other hand, only scalar connector fields could interpret the WMAP haze concerning the constraints of anomalous magnetic moment of leptons. Furthermore, if there is only one connector field for all the charged leptons, some lepton flavor violating decays could happen with too large branching ratios severely violating the experimental bounds.Comment: 15 pages, 3 figures, accepted for publication in Phys. Rev.

    Evidence for mirror dark matter from the CDMS low energy electron recoil spectrum

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    We point out that mirror dark matter predicts low energy (ER∼<2E_R \stackrel{<}{\sim} 2 keV) electron recoils from mirror electron scattering as well as nuclear recoils from mirror ion scattering. The former effect is examined and applied to the recently released low energy electron recoil data from the CDMS collaboration. We speculate that the sharp rise in electron recoils seen in CDMS below 2 keV might be due to mirror electron scattering and show that the parameters suggested by the data are roughly consistent with the mirror dark matter explanation of the annual modulation signal observed in the DAMA/Libra and DAMA/NaI experiments. Thus, the CDMS data offer tentative evidence supporting the mirror dark matter explanation of the DAMA experiments, which can be more rigorously checked by future low energy electron recoil measurements.Comment: about 9 pages, comments welcome
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