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# Solar and atmospheric neutrinos: Background sources for the direct dark matter searches

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Physik-Department E15, Technische Universität München, D-85748 Garching, Germany
(Impact Factor: 4.45). 03/2010; 34(2):90-96. DOI: 10.1016/j.astropartphys.2010.06.002
Source: arXiv

ABSTRACT In experiments for direct dark matter searches, neutrinos coherently scattering off nuclei can produce similar events as Weakly Interacting Massive Particles (WIMPs). The calculated count rate for solar neutrinos in such experiments is a few events per ton-year. This count rate strongly depends on the nuclear recoil energy threshold achieved in the experiments for the WIMP search. We show that solar neutrinos can be a serious background source for direct dark matter search experiments using Ge, Ar, Xe and CaWO4 as target materials. To reach sensitivities better than ∼10−10 pb for the elastic WIMP nucleon spin-independent cross section in the zero-background limit, energy thresholds for nuclear recoils should be ≳2.05 keV for CaWO4, ≳4.91 keV for Ge, ≳2.89 keV for Xe, and ≳8.62 keV for Ar as target material. Next-generation experiments should not only strive for a reduction of the present energy thresholds but mainly focus on an increase of the target mass. Atmospheric neutrinos limit the achievable sensitivity for the background-free direct dark matter search to ≳10−12 pb.

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Available from: F. von Feilitzsch, Dec 20, 2013
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• "In the near future, results from 100 kg-scale detectors may improve this sensitivity by an order of magnitude to the zeptobarn scale. Future ton-scale detectors are being planned to extend sensitivities even beyond that, with the ultimate goal of probing yoctobarn cross sections, where experiments will reach the background-free limit for non-directional detectors imposed by irreducible neutrino backgrounds [18] [19] (and also the outer limits of the metric prefix system). The single most studied dark matter candidate is the lightest neutralino χ predicted by supersymmetry (SUSY) [20] [21] [22] [23] [24]. "
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ABSTRACT: The International School for Advanced Studies (SISSA) was founded in 1978 and was the first institution in Italy to promote post-graduate courses leading to a Doctor Philosophiae (or PhD) degree. A centre of excellence among Italian and international universities, the school has around 65 teachers, 100 post docs and 245 PhD students, and is located in Trieste, in a campus of more than 10 hectares with wonderful views over the Gulf of Trieste. SISSA hosts a very high-ranking, large and multidisciplinary scientific research output. The scientific papers produced by its researchers are published in high impact factor, well-known international journals, and in many cases in the world's most prestigious scientific journals such as Nature and Science. Over 900 students have so far started their careers in the field of mathematics, physics and neuroscience research at SISSA. Visit www.sissa.it.
Journal of Cosmology and Astroparticle Physics 09/2010; 5(05). DOI:10.1088/1475-7516/2011/05/018 · 5.88 Impact Factor
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ABSTRACT: We study theoretical implications of direct dark matter searches in the minimal supersymmetric standard model (MSSM). We assume that no accidental cancellations occur in the spin-independent elastic neutralino-quark scattering cross section, but do not impose any relations among the weak-scale MSSM parameters. We show that direct detection cross section below 10^-44 cm^2 requires the lightest supersymmetric particle (LSP) neutralino to be close to either a pure gaugino or pure Higgsino limit, with smaller cross sections correlated with smaller admixture of the subdominant components. The current XENON100 bound rules out essentially all models in which the lightest neutralino has the Higgsino fraction between 0.2 and 0.8. Furthermore, smaller direct detection cross sections correlate with stronger fine-tuning in the electroweak symmetry breaking sector. In the gaugino LSP scenario, the current XENON100 bound already implies some fine-tuning: for example, at least 10% tuning is required if the LSP mass is above 70 GeV. In both gaugino and Higgsino LSP scenarios, the direct dark matter searches currently being conducted and designed should lead to a discovery if no accidental cancellations or fine-tuning at a level below 1% is present.
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