Double-β decay of116Cd

The NEMO-2 tracking detector located in the Fréjus Underground Laboratory was designed as a prototype of the detector NEMO-3 to study 0ν and 2ν double-beta decay (ββ) physics. After ten months of nearly continuous running with an enriched cadmium source (0.92 mol·y of¹¹⁶Cd) aββ2ν half-life ofT _1/2=(3.75±0.35(stat)±0.21(syst))·10¹⁹ y was measured. Limits with 90% CL on the¹¹⁶Cd half-lives of 5.0·10²¹ y forββ0ν decay and of 1.2·10²¹ y forββ0νχ ⁰ decay with a Majoron (χ ⁰) were obtained. Theoretical predictions for 0ν and 2ν decays of¹¹⁶Cd are also presented.     

Dirac fermions on graphite cones

The electronic structure of graphitic cones is investigated within the self-consistent field-theory model. The local and total density of states near the apex are found for cones of different opening angles. For extended electronic states, the total density of states is found to vanish at the Fermi level at any opening angles more than 60° In turn, for power-law localized states, normalized zero-energy modes are shown to emerge.     

Computational bounds for local search in combinatorial optimization

The results related to finding local optima in combinatorial optimization are overviewed. The class of polynomial-time local search problems (class PLS) is considered. By analogy with Cook’s theorem, the existence of most complicated problems in this class is established. The number of steps in local descent algorithms is estimated in the worst and average cases. The local search determination of exact and approximate solutions with guaranteed error bounds is discussed.     

Study of 2β-decay of 100Mo and 82Se using the NEMO3 detector

After analysis of 5797 h of data from the detector NEMO3, new limits on neutrinoless double beta decay of ¹⁰⁰Mo (T _1/2>3.1×10²³y, 90% CL) and ⁸²Se (_{T 1/2}>1.4×10²³y, 90% CL) have been obtained. The corresponding limits on the effective majorana neutrino mass are: 〈m _v〉<(0.8–1.2) eV and 〈m _v〉<(1.5–3.1) eV, respectively. Also the limits on double-beta decay with Majoron emission are: T _1/2>1.4×10²²y (90% CL) for ¹⁰⁰Mo and T _1/2>1.2×10²²y (90% CL) for ⁸²Se. Corresponding bounds on the Majoron-neutrino coupling constant are 〈 g _ee〉<(0.5–0.9)×10^?4 and <(0.7?1.6)×10^?4. Two-neutrino 2β-decay half-lives have been measured with a high accuracy, $T_{1/2}^{100_{Mo} } = [7.68 \pm 0.02(stat) \pm 0.54(syst)] \times 10^{18} y$ and $T_{1/2}^{82_{Se} } = [10.3 \pm 0.3(stat) \pm 0.7(syst)] \times 10^{19} y$ .     

First results of the search for neutrinoless double-beta decay with the NEMO 3 detector

The NEMO 3 detector, which has been operating in the Fréjus underground laboratory since February 2003, is devoted to the search for neutrinoless double-beta decay (beta beta 0v). The half-lives of the two neutrino double-beta decay (beta beta 2v) have been measured for 100Mo and 82Se. After 389 effective days of data collection from February 2003 until September 2004 (phase I), no evidence for neutrinoless double-beta decay was found from approximately 7 kg of 100Mo and approximately 1 kg of 82Se. The corresponding limits are T1/2(beta beta0v) > 4.6 x 10(23) yr for 100Mo and T1/2(beta beta 0v) > 1.0 x 10(23) yr for 82Se (90% C.L.). Depending on the nuclear matrix element calculation, the limits for the effective Majorana neutrino mass are < 0.7-2.8 e/v for 100Mo and < 1.7-4.9 eV for 82Se.     

SU(1, 1) coherence-preserving Hamiltonians: a path-integral approach

We consider the path integral for the SU(1, 1) dynamical group based on its associated coherent states. It is diagonalized with the help of a linear fractional transformation.