Extrapolation of NEMO Technique to Future Generation of 2β-Decay Experiments

Possibilities of NEMO technique for future neutrinoless double-beta-decay experiments are discussed. Main idea is to have a realistic project with planned sensitivity for half-life on the level (1-2) × 10²⁶ y (sensitivity to neutrino mass (0.05-0.1) eV). It is demonstrated that this can be achieved using improved NEMO technique to investigate 100 kg of ⁸²Se. Possible improvements of NEMO technique and background conditions are discussed. Scheme of future SUPERNEMO detector and main characteristics of experiment are presented. Such detector can be used also to investigate 0 decay in ¹⁰⁰Mo, ¹³⁰Te and ¹¹⁶Cd with sensitivity up to (5-10)×10²⁵ y (or with sensitivity to neutrino mass 0.1 eV).     

Measurement of dijet cross sections in <Emphasis Type="Italic">ep</Emphasis> interactions with a leading neutron at HERA

Measurements are reported of the production of dijet events with a leading neutron in ep interactions at HERA. Differential cross sections for photoproduction and deep inelastic scattering are presented as a function of several kinematic variables. Leading order QCD simulation programs are compared with the measurements. Models in which the real or virtual photon interacts with a parton of an exchanged pion are able to describe the data. Next-to-leading order perturbative QCD calculations based on pion exchange are found to be in good agreement with the measured cross sections. The fraction of leading neutron dijet events with respect to all dijet events is also determined. The dijet events with a leading neutron have a lower fraction of resolved photon processes than do the inclusive dijet data.Received: 31 January 2005, Revised: 7 March 2005, Published online: 28 April 2005     

Cluster models of light nuclei and the method of hyperspherical harmonics: Successes and challenges

Hyperspherical-harmonics method to investigate the lightest nuclei having three-cluster structure is discussed together with recent experiments. Properties of bound states and methods to explore three-body continuum are presented. The challenges created by large neutron excess and halo phenomena are highlighted. Astrophysical aspects of the ⁷Li + n → ⁸Li + γ reaction and the solar-boron-neutrinos problem are analyzed. Three-cluster structure of highly excited states in ⁸Be is shown to be responsible for extreme isospin mixing. Progress in studies of ⁶He- and ¹¹Li-induced inclusive and exclusive nuclear reactions is demonstrated, providing information on the nature of continuum structures of Borromean nuclei. The text was submitted by the authors in English.     

Collective sea-gull effect in πp interactions at 250 GeV/c

A collective “sea-gull” effect is observed for a system of fast hadrons produced in the fragmentation regions of nondiffractive π⁺p-interactions at 250 GeV/c. The effect is not reproduced by the FRITIOF fragmentation model in its details. It is demonstrated that hard-like processes, both in the collision phase and in the fragmentation phase, are not properly treated in the model.     

Search for anomalous weak dipole moments of the $\tau$ lepton

The anomalous weak dipole moments of the lepton are measured in a data sample collected by ALEPH from 1990 to 1995 corresponding to an integrated luminosity of 155 pb^-1. Tau leptons produced in the reaction at energies close to the mass are studied using their semileptonic decays to , , or . The real and imaginary components of both the anomalous weak magnetic dipole moment and the CP-violating anomalous weak electric dipole moment, , , and , are measured simultaneously by means of a likelihood fit built from the full differential cross section. No evidence of new physics is found. The following bounds are obtained (95% CL): , , , and .Received: 25 September 2002, Published online: 29 August 2003