Measurement of the double beta decay half-life of Nd-150 and search for neutrinoless decay modes with the NEMO-3 detector

Source: arXiv


The half-life for two-neutrino double beta decay of Nd-150 has been measured with data taken by the NEMO 3 experiment at the Modane Underground Laboratory. The limits are also set on the half-life of different neutrinoless double beta decay of this isotope. Comment: PhD thesis, the University of Manchester

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Available from: Nasim Fatemighomi, Apr 22, 2015
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    • "±10% external background precision ±0.3 [12] ±10% 150 Nd precision ±0.7 [11] "

    Full-text · Dataset · Jan 2014
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    • "At the moment, the most promising attempts to find lepton number violation are the experiments searching for neutrinoless double beta decay (0νββ). Several such experiments have been performed (IGEX [4], Heidelberg-Moscow [5], CUORICINO [6], NEMO [7], and others), so far without unambiguous detection. New second generation experiments like GERDA [8], which has been built and is being readied for data taking, will soon improve the sensitivity and may observe 0νββ. "
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    ABSTRACT: We evaluate the Schechter-Valle (Black Box) theorem quantitatively by considering the most general Lorentz invariant Lagrangian consisting of point-like operators for neutrinoless double beta decay. It is well known that the Black Box operators induce Majorana neutrino masses at four-loop level. This warrants the statement that an observation of neutrinoless double beta decay guarantees the Majorana nature of neutrinos. We calculate these radiatively generated masses and find that they are many orders of magnitude smaller than the observed neutrino masses and splittings. Thus, some lepton number violating New Physics (which may at tree-level not be related to neutrino masses) may induce Black Box operators which can explain an observed rate of neutrinoless double beta decay. Although these operators guarantee finite Majorana neutrino masses, the smallness of the Black Box contributions implies that other neutrino mass terms (Dirac or Majorana) must exist. If neutrino masses have a significant Majorana contribution then this will become the dominant part of the Black Box operator. However, neutrinos might also be predominantly Dirac particles, while other lepton number violating New Physics dominates neutrinoless double beta decay. Translating an observed rate of neutrinoless double beta decay into neutrino masses would then be completely misleading. Although the principal statement of the Schechter-Valle theorem remains valid, we conclude that the Black Box diagram itself generates radiatively only mass terms which are many orders of magnitude too small to explain neutrino masses. Therefore, other operators must give the leading contributions to neutrino masses, which could be of Dirac or Majorana nature.
    Full-text · Article · May 2011 · Journal of High Energy Physics
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