Relativistic configuration-interaction density functional theory: Nonaxial effects on nuclear $\beta \beta$ decay

Abstract

The relativistic configuration-interaction density functional theory is developed for even-even and odd-odd nuclei and is used to predict the nuclear matrix element of the neutrinoless $\beta \beta$ ($0\nu \beta \beta$) decay in nucleus ${}^{76}$Ge, amongst the most promising $\beta \beta$-decay candidates. The nonaxial deformation, i.e., triaxiality, which poses severe challenges in evaluating the nuclear matrix element of ${}^{76}$Ge, is incorporated within a full model space for the first time. The spectroscopic properties of the $\beta \beta$-decay partners ${}^{76}$Ge and ${}^{76}$Se, and the nuclear matrix element governing the two-neutrino $\beta \beta$ ($2\nu \beta \beta$) decay in ${}^{76}$Ge are well reproduced, providing solid examinations for the validity of theoretical calculations. The inclusion of the triaxial degree of freedom enhances the nuclear matrix element of the $0\nu \beta \beta$ decay significantly by a factor around two. The present results indicate that the goals of next-generation experiments searching for the $0\nu \beta \beta$ decay in ${}^{76}$Ge can be achieved using only a quarter amount of the experimental materials.

10 pages, 2 figures

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Cited by in corpus (4)

• Neutrinoless $\beta \beta$ decay nuclear matrix elements complete up to N${}^2$LO in heavy nuclei
• Subspace-projected multireference covariant density functional theory
• Two-neutrino $\beta \beta$ decay to excited states at next-to-leading order
• Implication of odd-even staggering in the charge radii of calcium isotopes