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K. Zuber

Publications and source records attributed to K. Zuber.

122 records · Page 7Linked to original sources
arXiv2000

Trimuon production in νN-scattering as a probe of massive neutrinos

The lepton-number violating process ν_μN \to μ^- μ^+ μ^+ X is studied for the first time in connection with Majorana neutrino masses of the second generation. The sensitivity for light and heavy Majorana neutrinos is investigated. The ratio with respect to the standard model charged current process is improved by some orders of magnitude if compared to previously discussed Majorana induced ΔL_μ = 2 processes. Non-observation of this process in previous experiments allows to demand the effective mass to be < m_{μμ} > \ls 10^4 GeV, being more stringent than previously discussed direct bounds, however still unnaturally high. Therefore, in the forseeable future, indirect bounds on effective masses other than m_{ee} will be more stringent.

hep-ph↗
arXiv2000

Signatures of heavy Majorana neutrinos and HERA's isolated lepton events

The graph of neutrinoless double beta decay is applied to HERA and generalized to final states with any two charged leptons. Considered is the case in which one of the two escapes typical identification criteria and the case when a produced tau decays hadronically. Both possibilities give one isolated lepton with high transverse momentum, hadronic activity and an imbalance in transverse momentum. We examine the kinematical properties of these events and compare them with the high p_T isolated leptons reported by the H1 collaboration. Their positive charged muon events can be explained by the ``double beta'' process and we discuss possibilities for the precise determination which original final state produced the single isolated lepton. To confirm our hypothesis one should search in the data for high pseudorapidity and/or low p_T leptons or for additional separated jets.

hep-ph↗
arXiv2000

Double beta decay with large scale Yb-loaded scintillators

The potential of large scale Yb-loaded liquid scintillators as proposed for solar neutrino spectroscopy are investigated with respect to double beta decay. The potential for beta-beta- - decay of 176Yb as well as the beta+/EC - decay for 168Yb is discussed. Not only getting for the first time an experimental half-life limit on 176Yb - decay, this will even be at least comparable or better than existing ones from other isotopes. Also for the first time a realistic chance to detect beta+/EC - decay exists. Effects of MeV-neutrinos are discussed as well.

nucl-ex↗
arXiv2000

New limits on effective Majorana neutrino masses from rare kaon decays

The rare kaon decay $K^+ \ra π^- μ^+ μ^+$ is violating lepton number by two units and is investigated within the context of Majorana neutrino masses. Using a new upper bound for this decay from E865 an upper limit on the effective Majorana mass term $\m_{μμ} < 500$ GeV could be obtained. This is improving existing bounds by about one order of magnitude. Implications on heavy neutrinos are discusse d as well as future possibilities to improve limits on this as well as other elements of the Majorana m ass matrix are investigated.

hep-ph↗
arXiv2000

Non-accelerator neutrino mass searches

The current status of non-accelerator based searches for effects of a non-vanishing neutrino mass is reviewed. Beside the direct kinematical methods this includes searches for magnetic moments and a discussion of the solar neutrino problem. Double beta decay is not included.

hep-ph↗
arXiv1999

Footprints of the Newly-Discovered Vela Supernova in Antarctic Ice Cores?

The recently-discovered, nearby young supernova remnant in the southeast corner of the older Vela supernova remnant may have been seen in measurements of nitrate abundances in Antarctic ice cores. Such an interpretation of this twenty-year-old ice-core data would provide a more accurate dating of this supernova than is possible purely using astrophysical techniques. It permits an inference of the supernova4s ${}^{44}$Ti yield purely on an observational basis, without reference to supernova modelling. The resulting estimates of the supernova distance and light-arrival time are 200 pc and 700 years ago, implying an expansion speed of 5,000 km/s for the supernova remnant. Such an expansion speed has been argued elsewhere to imply the explosion to have been a 15 $M_\odot$ Type II supernova. This interpretation also adds new evidence to the debate as to whether nearby supernovae can measurably affect nitrate abundances in polar ice cores.

astro-ph↗
arXiv1999

Terrestrial neutrino mass searches

The current status of direct terrestrial neutrino mass searches is presented. This includes direct kinematical searches, double beta decay and the search for a magnetic moment.

hep-ph↗
arXiv1998

On the physics of massive neutrinos

Massive neutrinos open up the possibility for a variety of new physical phenomena. Among them are oscillations and double beta decay. Furthermore they influence several fields from particle physics to cosmology. In this article the concept of massive neutrinos is given and the current status of experimental research is extensively reviewed. This includes astrophysical studies of solar, supernova and very high energy neutrinos. Future perspectives are also outlined.

hep-ph↗
arXiv1998

Long baseline neutrino oscillations

The motivation for possible future long baseline neutrino experiments is discussed. The proposed experiments as well as their physics potential is reviewed.

hep-ex↗
arXiv1997

Status of neutrino oscillation searches

The current status of neutrino oscillation searches with reactors and accelerators is reviewed. An outlook, especially on future long baseline neutrino oscillation projects, is given.

hep-ph↗
arXiv1996

Neutrino oscillations and dark matter

The significance of light massive neutrinos as hot dark matter is outlined. The power of neutrino oscillation experiments with respect to detect such neutrinos in the eV-region is discussed. Present hints for neutrino oscillations in solar, atmospheric and LSND data are reviewed as well as future experiments and their potential.

hep-ph↗
arXiv1996

MeV neutrinos in double beta decay

The effect of Majorana neutrinos in the MeV mass range on the double beta decay of various isotopes is studied on pure phenomenological arguments. By using only experimental half life data, limits on the mixing parameter $U_{eh}^2$ of the order 10$^{-7}$ can be derived. Also the possible achievements of upcoming experiments and some consequences are outlined.

hep-ph↗