Resonance enhancement of neutrinoless double electron capture |
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Authors: | MI Krivoruchenko Fedor Šimkovic Dieter Frekers Amand Faessler |
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Institution: | 1. Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow, Russia;2. Department of Nano-, Bio-, Information and Cognitive Technologies, Moscow Institute of Physics and Technology, 9 Institutskii per., 141700 Dolgoprudny, Moscow Region, Russia;3. Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna, Moscow Region, Russia;4. Department of Nuclear Physics and Biophysics, Comenius University, Mlynská dolina F1, SK-842 48 Bratislava, Slovakia;5. Institut für Kernphysik, Universität Münster, Wilhelm-Klemm-Str. 9, 48149 Münster, Germany;6. Institut für Theoretische Physik, Tübingen Universität, Auf der Morgenstelle 14, D-72076 Tübingen, Germany |
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Abstract: | The process of neutrinoless double electron (0νECEC) capture is revisited for those cases where the two participating atoms are nearly degenerate in mass. The theoretical framework is the formalism of an oscillation of two atoms with different total lepton number (and parity), one of which can be in an excited state so that mass degeneracy is realized. In such a case and assuming light Majorana neutrinos, the two atoms will be in a mixed configuration with respect to the weak interaction. A resonant enhancement of transitions between such pairs of atoms will occur, which could be detected by the subsequent electromagnetic de-excitation of the excited state of the daughter atom and nucleus. Available data of atomic masses, as well as nuclear and atomic excitations are used to select the most likely candidates for the resonant transitions. Assuming an effective mass for the Majorana neutrino of 1 eV, some half-lives are predicted to be as low as 1022 years in the unitary limit. It is argued that, in order to obtain more accurate predictions for the 0νECEC half-lives, precision mass measurements of the atoms involved are necessary, which can readily be accomplished by today?s high precision Penning traps. Further advancements also require a better understanding of high-lying excited states of the final nuclei (i.e. excitation energy, angular momentum and parity) and the calculation of the nuclear matrix elements. |
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Keywords: | Neutrino mass Neutrinoless double beta decay Double electron capture Nuclear matrix elements |
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