Neutrino propagation in nuclear medium and neutrinoless double-β decay.
We discuss a novel effect in neutrinoless double-β (0νββ) decay related with the fact that its underlying mechanisms take place in the nuclear matter environment. We study the neutrino exchange mechanism and demonstrate the possible impact of nuclear medium via lepton-number-violating (LNV) four-fermion interactions of neutrinos with quarks from a decaying nucleus. The net effect of these interactions is the generation of an effective in-medium Majorana neutrino mass matrix. The enhanced rate of the 0νββ decay can lead to the apparent incompatibility of observations of the 0νββ decay with the value of the neutrino mass determined or restricted by the β-decay and cosmological data. The effective neutrino masses and mixing are calculated for the complete set of the relevant four-fermion neutrino-quark operators. Using experimental data on the 0νββ decay in combination with the β-decay and cosmological data, we evaluate the characteristic scales of these operators: ΛLNV≥2.4  TeV.
Universidad Técnica Federico Santa María, Centro-Cientifico-Tecnológico de Valparaiso, Casilla 110-V, Valparaiso, Chile.
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S
Kovalenko
Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow, Russia and Department of Nano-, Bio-, Information, and Cognitive Technologies, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia.
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MI
Krivoruchenko
Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna, Russia and Department of Nuclear Physics and Biophysics, Comenius University, Mlynská Dolina F1, SK-842 48 Bratislava, Slovakia and Czech Technical University in Prague, CZ-12800 Prague, Czech Republic.
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F
Simkovic