arXiv subjects

H. V. Klapdor-Kleingrothaus

Publications and source records attributed to H. V. Klapdor-Kleingrothaus.

At least 55 records · Page 3Linked to original sources

arXiv2002

Implications of observed neutrinoless double beta decay

Recently a positive indication of the neutrinoless double beta decay has been announced. We study the implications of this result taking into consideration earlier results on atmospheric neutrinos and solar neutrinos. We also include in our discussions the recent results from SNO and K2K. We point out that on the confidence level given for the double beta signal, the neutrino mass matrices are now highly constrained. All models predicting Dirac masses are ruled out and leptogenesis becomes a natural choice. Only the degenerate and the inverted hierarchical solutions are allowed for the three generation Majorana neutrinos. In both these cases we find that the radiative corrections destabilize the solutions and the LOW, VO and Just So solutions of the solar neutrinos are ruled out. For the four generation case only the inverted hierarchical scenario is allowed.

hep-ph↗

arXiv2001

Sneutrino-induced like sign dilepton signal with conserved R-parity

Lepton number violation could be manifest in the sneutrino sector of supersymmetric extensions of the standard model with conserved R-parity. Then sneutrinos decay partly into the ``wrong sign charged lepton'' final state, if kinematically accessible. In sneutrino pair production or associated single sneutrino production, the signal then is a like sign dilepton final state. Under favourable circumstances, such a signal could be visible at the LHC or a next generation linear collider for a relative sneutrino mass-splitting of order ${\cal O}(0.001)$ and sneutrino width of order ${\cal O}$(1 GeV). On the other hand, the like sign dilepton event rate at the TEVATRON is probably too small to be observable.

hep-ph↗

arXiv2001

New Underground Neutrino Observatory - GENIUS- in the New Millenium : for Solar Neutrinos, Dark Matter and Double Beta Decay

Double beta decay is indispensable to solve the question of the neutrino mass matrix together with $ν$ oscillation experiments. The most sensitive experiment since eight years - the Heidelberg-Moscow experiment in Gran-Sasso - already now, with the experimental limit of < m_ν> < 0.26 eV excludes degenerate $ν$ mass scenarios allowing neutrinos as hot dark matter in the universe for the small angle MSW solution of the solar neutrino problem. It probes cosmological models including hot dark matter already now on the level of future satellite experiments MAP and PLANCK. It further probes many topics of beyond Standard Model physics at the TeV scale. Future experiments should give access to the multi-TeV range and complement on many ways the search for new physics at future colliders like LHC and NLC. For neutrino physics GENIUS will allow to test almost all neutrino mass scenarios allowed by the present neutrino oscillation experiments. At the same time GENIUS will cover a wide range of the parameter space of predictions of SUSY for neutralinos as cold dark matter. Further it has the potential to be a real-time detector for low-energy (pp and 7Be) solar neutrinos. A GENIUS Test Facility has just been funded and will come into operation by end of 2001.

hep-ph↗

arXiv2001

Status of the HDMS experiment, the GENIUS project and the GENIUS-TF

The status of dark matter search in Heidelberg is reviewed. After one year of running the HDMS prototype experiment in the Gran Sasso Underground Laboratory, the inner crystal of the detector has been replaced with a HPGe crystal of enriched 73Ge. The results of the operation of the HDMS prototype detector are discussed. In the light of the contradictive results from the CDMS and DAMA experiments the GENIUS-TF, a new experimental setup is proposed. The GENIUS-TF could probe the DAMA evidence region using the WIMP nucleus recoil signal and WIMP annual modulation signature simulataneously. Besides that it can prove some key parameters of the detector technique, to be implemented into the GENIUS setup and will in this sense be a first step towards the realization of the GENIUS experiment.

hep-ph↗

arXiv2001

Neutrinoless double beta decay potential in a large mixing angle world

We discuss the possibility of reconstructing the neutrino mass spectrum from the complementary processes of neutrino oscillations and double beta decay in view of the new data of Super-Kamiokande presented at the Neutrino2000 conference. Since the large mixing angle solution is favored, now, the prospects to observe double beta decay and provide informations on the absolute mass scale in the neutrino sector have been improved.

hep-ph↗

arXiv2001

Information about the neutrino mass matrix from Double Beta Decay

Double beta decay is indispensable to solve the question of the neutrino mass matrix together with neutrino oscillation experiments. The most sensitive experiment since eight years - the Heidelberg-Moscow experiment in Gran-Sasso - already now, with the experimental limit of < m_ν> < 0.26 eV excludes degenerate neutrino mass scenarios allowing neutrinos as hot dark matter in the universe for the small angle MSW solution of the solar neutrino problem. It probes cosmological models including hot dark matter already now on the level of future satellite experiments MAP and PLANCK. It further probes many topics of beyond Standard Model physics at the TeV scale. Future experiments should give access to the multi-TeV range and complement on many ways the search for new physics at future colliders like LHC and NLC. For neutrino physics some of them (GENIUS) will allow to test almost all neutrino mass scenarios allowed by the present neutrino oscillation experiments. A GENIUS Test Facility has just been funded and will come into operation by end of 2001.

hep-ph↗

arXiv2001

Recent Results from the HDMS Experiment

The status of dark matter search with the HDMS experiment is reviewed. After one year of running the HDMS prototype detector in the Gran Sasso Underground Laboratory, the inner crystal of the detector has been replaced with a HPGe crystal of enriched 73Ge. The results of the operation of the HDMS prototype detector are discussed.

hep-ph↗

arXiv2001

GENIUS and the Genius TF: A New Observatory for WIMP Dark Matter and Neutrinoless Double Beta Decay

The GENIUS proposal is described and some of it's physics potential is outlined. Also in the light of the contradictive results from the DAMA and CDMS experiments the Genius TF, a new experimental setup is proposed. The Genius TF could probe the DAMA evidence region using the WIMP nucleus recoil signal and WIMP annual modulation signature simultaneously. Besides that it can prove the long term feasibility of the detector technique to be implemented into the GENIUS setup and will in this sense be a first step towards the realization of the GENIUS experiment.

hep-ph↗

arXiv2001

Latest Results from the Heidelberg-Moscow Double Beta Decay Experiment

New results for the double beta decay of 76Ge are presented. They are extracted from Data obtained with the HEIDELBERG-MOSCOW, which operates five enriched 76Ge detectors in an extreme low-level environment in the GRAN SASSO. The two neutrino accompanied double beta decay is evaluated for the first time for all five detectors with a statistical significance of 47.7 kg y resulting in a half life of (T_(1/2))^(2nu) = [1.55 +- 0.01 (stat) (+0.19) (-0.15) (syst)] x 10^(21) years. The lower limit on the half-life of the 0nu beta-beta decay obtained with pulse shape analysis is (T_(1/2))^(0_nu) > 1.9 x 10^(25) [3.1 x 10^(25)] years with 90% C.L. (68% C.L.) (with 35.5 kg y). This results in an upper limit of the effective Majorana neutrino mass of 0.35 eV (0.27 eV). No evidence for a Majoron emitting decay mode or for the neutrinoless mode is observed.

hep-ph↗

arXiv2001

New Physics in the New Millennium with GENIUS: Double Beta Decay, Dark Matter, Solar Neutrinos

Double beta decay is indispensable to solve the question of the neutrino mass matrix together with $ν$ oscillation experiments. The most sensitive experiment since eight years - the Heidelberg-Moscow experiment in Gran-Sasso - already now, with the experimental limit of $ < 0.26$ eV excludes degenerate $ν$ mass scenarios allowing neutrinos as hot dark matter in the universe for the small angle MSW solution of the solar neutrino problem. It probes cosmological models including hot dark matter already now on the level of future satellite experiments MAP and PLANCK. It further probes many topics of beyond Standard Model physics at the TeV scale. Future experiments should give access to the multi-TeV range and complement on many ways the search for new physics at future colliders like LHC and NLC. For neutrino physics some of them (GENIUS) will allow to test almost all neutrino mass scenarios allowed by the present neutrino oscillation experiments. At the same time GENIUS will cover a wide range of the parameter space of predictions of SUSY for neutralinos as cold dark matter. Further it has the potential to be a real-time detector for low-energy ($pp$ and $^7$Be) solar neutrinos. A GENIUS Test Facility has just been funded and will come into operation by end of 2001.

hep-ph↗

arXiv2001

Neutrino Mass from Laboratory: Contribution of Double Beta Decay to the Neutrino Mass Matrix

Double beta decay is indispensable to solve the question of the neutrino mass matrix together with $ν$ oscillation experiments. The most sensitive experiment - since eight years the HEIDELBERG-MOSCOW experiment in Gran-Sasso - already now, with the experimental limit of $ < 0.26$ eV practically excludes degenerate $ν$ mass scenarios allowing neutrinos as hot dark matter in the universe for the smallangle MSW solution of the solar neutrino problem. It probes cosmological models including hot dark matter already now on the level of future satellite experiments MAP and PLANCK. It further probes many topics of beyond SM physics at the TeV scale. Future experiments should give access to the multi-TeV range and complement on many ways the search for new physics at future colliders like LHC and NLC. For neutrino physics some of them (GENIUS) will allow to test almost all neutrino mass scenarios allowed by the present neutrino oscillation experiments.

hep-ph↗

arXiv2001

GENIUS - A New Facility of Non-Accelerator Particle Physics

The GENIUS (\underline {Ge}rmanium in Liquid \underline {Ni}trogen \underline {U}nderground \underline {S}etup) project has been proposed in 1997 \cite{KK-BEY97} as first third generation double beta decay project, with a sensitivity aiming down to a level of an effective neutrino mass of $ \sim$ 0.01 - 0.001 eV. Such sensitivity has been shown to be indispensable to solve the question of the structure of the neutrino mass matrix which cannot be solved by neutrino oscillation experiments alone \cite{KKPS}. It will allow broad access also to many other topics of physics beyond the Standard Model of particle physics at the multi-TeV scale. For search of cold dark matter GENIUS will cover almost the full range of the parameter space of predictions of SUSY for neutralinos as dark matter \cite{KK-Ram,Bed-KK2}. Finally, GENIUS has the potential to be the first real-time detector for low-energy (pp and $^7{Be}$) solar neutrinos \cite{Bau-KK,KKPropos99}. A GENIUS-Test Facility has just been funded and will come into operation by end of 2001.

hep-ph↗

arXiv2001

Higgs Bosons and the Indirect Search for WIMPs

We investigated the contribution of the MSSM Higgs bosons produced in the neutralino annihilation in the Earth and Sun to the total WIMPs detection signals. We found that this contribution is very important and results in a lower bound for the muon flux from the Sun of 10^{-7} - 10^{-8} m^{-2} yr^{-1} for neutralinos heavier than 200 GeV. We noticed that due to the SUSY charged Higgs bosons one can expect an energetic tau neutrino flux from the Sun at a level of 10^2 m^{-2} yr^{-1}.

hep-ph↗

arXiv2000

Update of the direct detection of dark matter and the role of the nuclear spin

We update our exploration of the MSSM parameter space at the weak scale where new accelerator and cosmological constraints are respected. The dependence of WIMP-nucleon cross sections on parameters of the MSSM, uncertainties of the nucleon structure and other theoretical assumptions like universality and co-annihilation are considered. In particular, we find that the coannihilation does not have a significant effect in our analysis in certain regions which are allowed even with coannihilation. The new cosmological constraint on the relic neutralino density used in the form $0.1 < Ω_χh^2_0<0.3$ does also not significantly affect the regions of allowed neutralino-nucleon cross sections. We notice that for nuclear targets with spin the spin-dependent interaction may determine the lower bound for the direct detection rate when the cross section of the scalar interaction drops below about $10^{-12} $pb.

hep-ph↗

arXiv2000

Double-beta decay matrix elements for Ge-76

Double-beta decay matrix elements (ME) for $^{76}Ge$ are calculated with different quasi random phase approximation (QRPA)-based methods. First, the ME for the two-neutrino mode are computed using two choices for the single particle (s.p.) basis: i) $2-4\hbarω$ full shells and ii) $3-4\hbarω$ full shells. When calculated with the renormalized QRPA (RQRPA) and full-RQRPA their values are rather dependent on the size of the single particle basis used, while calculated with proton-neutron QRPA (pnQRPA) and second-QRPA approaches such a dependence was found to be small. The Ikeda sum rule was well fulfilled within pnQRPA for both choices of the s.p. basis and with a good approximation within second-QRPA, while the RQRPA and full-RQRPA methods give deviations up to 21%. Further, the ME for the neutrinoless mode are calculated with the pnQRPA, RQRPA and full-RQRPA methods. They all give close results for the calculation with the smaller basis (i), while for the larger basis (ii), the results differ significantly either from one method to another or within the same method. Finally, using the most recent experimental limit for the $0νββ$ decay half-life of $^{76}Ge$ a critical discussion on the upper limits for the neutrino mass parameter obtained with different theoretical approaches is given.

nucl-th↗

arXiv2000

Neutrino mass spectrum and neutrinoless double beta decay

The relations between the effective Majorana mass of the electron neutrino, $m_{ee}$, responsible for neutrinoless double beta decay, and the neutrino oscillation parameters are considered. We show that for any specific oscillation pattern $m_{ee}$ can take any value (from zero to the existing upper bound) for normal mass hierarchy and it can have a minimum for inverse hierarchy. This means that oscillation experiments cannot fix in general $m_{ee}$. Mass ranges for $m_{ee}$ can be predicted in terms of oscillation parameters with additional assumptions about the level of degeneracy and the type of hierarchy of the neutrino mass spectrum. These predictions for $m_{ee}$ are systematically studied in the specific schemes of neutrino mass and flavor which explain the solar and atmospheric neutrino data. The contributions from individual mass eigenstates in terms of oscillation parameters have been quantified. We study the dependence of $m_{ee}$ on the non-oscillation parameters: the overall scale of the neutrino mass and the relative mass phases. We analyze how forthcoming oscillation experiments will improve the predictions for $m_{ee}$. On the basis of these studies we evaluate the discovery potential of future \znbb decay searches. The role \znbb decay searches will play in the reconstruction of the neutrino mass spectrum is clarified. The key scales of $m_{ee}$, which will lead to the discrimination among various schemes are: $m_{ee} \sim 0.1$ eV and $m_{ee} \sim 0.005$ eV.

hep-ph↗

arXiv2000

First Results from the Heidelberg Dark Matter Search Experiment

The Heidelberg Dark Matter Search Experiment (HDMS) is a new ionization Germanium experiment in a special design. Two concentric Ge crystals are housed by one cryostat system, the outer detector acting as an effective shield against multiple scattered photons for the inner crystal, which is the actual dark matter target. We present first results after successfully running the prototype detector for a period of about 15 months in the Gran Sasso Underground Laboratory. We analyze the results in terms of limits on WIMP-nucleon cross sections and present the status of the full scale experiment, which will be installed in Gran Sasso in the course of this year.

astro-ph↗

arXiv2000

A superformula for neutrinoless double beta decay II: The short range part

A general Lorentz-invariant parameterization for the short-range part of the 0vBB decay rate is derived. Combined with the long range part already published this general parameterization in terms of effective B-L violating couplings allows one to extract the 0vBB limits on arbitrary lepton number violating theories.

hep-ph↗