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H. V. Klapdor-Kleingrothaus

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

At least 73 records · Page 4Linked to original sources
arXiv2000

Confronting Dilaton-exchange gravity with experiments

We study the experimental constraints on theories, where the equivalence principle is violated by dilaton-exchange contributions to the usual graviton-exchange gravity. We point out that in this case it is not possible to have any CPT violation and hence there is no constraint from the CPT violating measurements in the $K-$system. The most stringent bound is obtained from the $K_L - K_S$ mass difference. In contrast, neither neutrino oscillation experiments nor neutrinoless double beta decay imply significant constraints.

hep-ph↗
arXiv2000

On nuclear matrix element uncertainties in short range 0vBB decay

The evaluation of short range contributions to neutrinoless double beta decay has been challenged due to critics of the ansatz of the nuclear matrix element calculations. We comment on the critics and uncertainties of these calculations and the effect on the derived limits.

hep-ph↗
arXiv2000

Effects of quantum space time foam in the neutrino sector

We discuss violations of CPT and quantum mechanics due to interactions of neutrinos with space-time quantum foam. Neutrinoless double beta decay and oscillations of neutrinos from astrophysical sources (supernovae, active galactic nuclei) are analysed. It is found that the propagation distance is the crucial quantity entering any bounds on EHNS parameters. Thus, while the bounds from neutrinoless double beta decay are not significant, the data of the supernova 1987a imply a bound being several orders of magnitude more stringent than the ones known from the literature. Even more stringent limits may be obtained from the investigation of neutrino oscillations from active galactic nuclei sources, which have an impressive potential for the search of quantum foam interactions in the neutrino sector.

hep-ph↗
arXiv2000

GENIUS - a Supersensitive Germanium Detector System for Rare Events

To increase by a major step the present sensitivity for dark matter and double beta decay search, a new project is suggested, which would operate 'naked' GErmanium detectors in liquid NItrogen as shielding in an Underground Setup (GENIUS). In a first step using 100 kg of natural Ge a large part of the MSSM parameter space for prediction of neutralinos as cold dark matter will be covered making the experiment complementary to LHC in the search for supersymmetry. In the second step use of one ton of enriched 76Ge would yield a sensitivity for double beta decay for the effective Majorana neutrino mass of \0.01 eV. This would be a breakthrough for neutrino physics. GENIUS would also be a breakthrough into the multi-TeV range for many other beyond standard models currently discussed, and the sensitivity would be comparable or even superior to LHC or NLC for various quantities such as right-handed W boson mass, R-parity violation, leptoquark or compositeness searches, or left-handed heavy neutrinos.

hep-ph↗
arXiv2000

Neutrino Majorana Mass and Baryon Number of the Universe below the Electroweak Symmetry breaking Scale

If the neutrino is Majorana type and the electroweak phase transition is second or weak first order, neutrino-induced interactions together with sphaleron transitions have the potential to erase a previously generated baryon asymmetry of the universe. Taking correctly into account the evolution of the vacuum expectation of the Higgs field the effective light neutrino masses are constrained to be lighter than order 10 MeV, while the effective heavy masses are constrained to be heavier than order 10^7 GeV.

hep-ph↗
arXiv2000

Lepton number violating interactions and their effects on neutrino oscillation experiments

Mixing between bosons that transform differently under the standard model gauge group, but identically under its unbroken subgroup, can induce interactions that violate the total lepton number. We discuss four-fermion operators that mediate lepton number violating neutrino interactions both in a model-independent framework and within supersymmetry (SUSY) without R-parity. The effective couplings of such operators are constrained by: i) the upper bounds on the relevant elementary couplings between the bosons and the fermions, ii) by the limit on universality violation in pion decays, iii) by the data on neutrinoless double beta decay and, iv) by loop-induced neutrino masses. We find that the present bounds imply that lepton number violating neutrino interactions are not relevant for the solar and atmospheric neutrino problems. Within SUSY without R-parity also the LSND anomaly cannot be explained by such interactions, but one cannot rule out an effect model-independently. Possible consequences for future terrestrial neutrino oscillation experiments and for neutrinos from a supernova are discussed.

hep-ph↗
arXiv2000

SUSY spectrum constraints on direct dark matter detection

We perform an investigation of the MSSM parameter space at the Fermi scale taking into account available accelerator, non-accelerator and cosmological constraints. Extra assumptions about upper bounds for some of the SUSY particles are also imposed. We show that a non-observation of the SUSY dark matter candidates with a high-accuracy dark matter detector, such as Ge-73, under above-mentioned assumptions can exclude large domains of the MSSM parameter space and, for instance, can make especially desirable collider search for light SUSY charged Higgs boson.

hep-ph↗
arXiv2000

Comment on ``Closing the neutrinoless double beta decay window into VEP and/or VLI''

The constraints from the non-observation of neutrinoless double beta decay on the violations of Lorentz invariance (VLI) or violations of the equivalence principle (VEP) have recently been re-examined (hep-ph/9904298) and it was claimed that the constraints are not valid. In this reply we point out that this statement is not correct and prove that the arguments given are wrong.

hep-ph↗
arXiv2000

New exotics in the double beta decay contributions zoo

We discuss the potential of neutrinoless double beta decay for testing Lorentz invariance and the weak equivalence principle as well as contributions from dilaton exchange gravity in the neutrino sector. While neutrino oscillation bounds constrain the region of large mixing of the weak and gravitational eigenstates, we obtain new constraints on violations of Lorentz invariance and the equivalence principle from neutrinoless double beta decay, applying even in the case of no mixing. Double beta decay thus probes a totally unconstrained region in the parameter space.

hep-ph↗
arXiv2000

Collider Signatures of Sneutrino Cold Dark Matter

Decays of sneutrinos are considered in the case that in the presence of lepton-number violation in the sneutrino sector the lighter tau-sneutrino is the Lightest Supersymmetric Particle and the Cold Dark Matter in the Universe. In such circumstances the signals from sparticle decays differ considerably from the ``standard'' case where the lightest neutralino is the Lightest Supersymmetric Particle and it is found that in a wide range of parameters compatible with the sneutrino Cold Dark Matter hypothesis signatures characteristic for such a scenario should be easily observable at for example a Next Linear Collider.

hep-ph↗
arXiv2000

Light Lepton Number Violating Sneutrinos and the Baryon Number of the Universe

Recent results of neutrino oscillation experiments point to a nonvanishing neutrino mass. Neutrino mass models favour Majorana-type neutrinos. In such circumstances it is natural that the supersymmetric counterpart of the neutrino, the sneutrino, bears also lepton number violating properties. On the other hand, the fact that the universe exhibits an asymmetry in the baryon and antibaryon numbers poses constraints on the extent of lepton number violation in the light sneutrino sector if the electroweak phase transition is second or weak first order. From the requirement that the Baryon Asymmetry of the Universe should not be washed out by sneutrino induced lepton number violating interactions and sphalerons below the critical temperature of the electroweak phase transition we find that the mass splitting of the light sneutrino mass states is compatible with the sneutrino Cold Dark Matter hypothesis only for heavy gauginos and opposite sign gaugino mass parameters.

hep-ph↗
arXiv2000

Direct Detection of Nonbaryonic Dark Matter

Weakly Interacting Massive Particles (WIMPs) are leading candidates for the dominant part of the mass density of the Universe. Here we will review direct WIMP detection techniques by giving examples of currently running experiments, and present the status of the most promising future projects.

astro-ph↗
arXiv2000

GENIUS: the first real-time detector for solar pp-neutrinos?

The GENIUS project is a proposal for a large supersensitive Germanium detector system for WIMP and double beta decay searches with a much increased sensitivity relative to existing and other future experiments. In this paper, the possibility to detect low energy solar neutrinos with GENIUS in real-time through elastic neutrino-electron scattering is studied.

astro-ph↗
arXiv2000

Neutrinoless double beta decay and new physics in the neutrino sector

Neutrinoless double beta decay belongs to the most sensitive tools for the search of new physics beyond the standard model. The recent half life limit of the Heidelberg-Moscow experiment implies restrictive bounds on the absolute mass scale in the neutrino sector. Possible improvements by the GENIUS project provide a unique possibility to reconstruct the neutrino mass spectrum. Further constraints on new interactions in the neutrino sector are given in a model-independent way. Consequences for neutrino anomalies and theories beyond the standard model such as left-right symmetric models, R-parity violating SUSY and leptoquarks are discussed. The potential of double beta decay experiments in the search for WIMP dark matter is reviewed.

hep-ph↗
arXiv1999

Digital Pulseshape Analysis by Neural Networks for the Heidelberg-Moscow-Double-Beta-Decay-Experiment

The Heidelberg-Moscow Experiment is presently the most sensitive experiment looking for neutrinoless double-beta decay. Recently the already very low background has been lowered by means of a Digital Pulseshape Analysis using a one parameter cut to distinguish between pointlike events and multiple scattered events. To use all the information contained in a recorded digital pulse, we developed a new technique for event recognition based on neural networks.

hep-ex↗
arXiv1999

Neutrino mass and magnetic moment in supersymmetry without R-parity in the light of recent data

We consider the generation of neutrino Majorana mass and transition magnetic moment by the lepton-number violating $λ$ and/or $λ'$ couplings in R-parity-violating supersymmetric models. We update (and improve) the existing upper limits on the relevant couplings using the most recent data on neutrino masses and mixings, indicating also the possible improvement by the GENIUS project. We study the implication of this update on the induced neutrino magnetic moment.

hep-ph↗
arXiv1999

Stellar Weak Interaction Rates and Energy Losses for fp-Shell Nuclei in the Proton-Neutron Quasiparticle Random-Phase Approximation

Nuclear weak interaction rates for fp-shell nuclei in stellar matter and the associated energy losses are calculated using a modified form of proton-neutron quasiparticle RPA model with separable Gamow-Teller forces. The stellar weak rates are calculated over a wide range of densities (10 < ρY_{e} (gcm^{-3}) < 10^{11}) and temperatures (10^{7} < T(K) < 30 x 10^{9}). This is the first ever extensive compilation of weak interaction rates in stellar matter calculated over a wide temperature-density grid and over a larger mass range. The calculated capture and decay rates take into consideration the latest experimental energy levels and ft value compilations. We have calculated stellar weak interaction rates for a total of 619 nuclei in the mass range A = 40 to 100. These also include many important neutron-rich nuclei which play an important role in the evolution process of stellar collapse. This is our second paper in a series where we will be presenting our results on an abbreviated scale of temperature and density for the mass range A = 18 to 100. This paper contains the stellar weak rates in the mass range 40 to 60.

nucl-th↗