First Results of the Search for Neutrinoless Double-Beta Decay with the NEMO 3 Detector

Abstract

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 <mv> < 0.7-2.8 e/v for 100Mo and <mv> < 1.7-4.9 eV for 82Se.

Measurement of the two neutrino double beta decay half-life of Zr-96 with the NEMO-3 detector

“…The total mass of the enriched ZrO 2 is 22.0 g of which 9.4 ± 0.2 g is 96 Zr [7]. NEMO-3 results thus far are published in [8,9,10,11].…”

Large ν ‐ ν ¯ $$ \nu \hbox{-} \overline{\nu} $$ oscillations from high-dimensional lepton number violating operator

“…As a result, it is concluded that the new long-range mode induced by O 7 gives the dominant contribution to the 0νββ decays in the present scenario. By comparing the current experimental limits on the 0νββ half-life of different nuclei [64][65][66][67][68][69][70], we can actually give the strong constraints to the Wilson coefficient C ud ee by assuming Λ ∼ 1 TeV. The numerical limits are collected in table 1, from which it is seen that the strongest constraint is given by the target 136 Xe [65,66] with |C ud ee | < 1.9 × 10 −4 .…”

Direct search for heavy neutral gauge bosons in the dielectron channel at D0

“…is not yet known, and is the subject of investigation [10]. Table 2.1: The three generations of leptons.…”