Shape transition of Nd and Sm isotopes and neutrinoless double-beta decay nuclear matrix element of ${}^{150}$Nd

Abstract

Neutron-rich Nd and Sm isotopes are known to exhibit shape phase transition as a function of neutron number. Among them, ${}^{150}$Nd and ${}^{150}$Sm are important not only because they are transitional nuclei, but also the parent and daughter nuclei of double-beta decay. We performed large-scale shell-model calculations of even-even Nd and Sm isotopes including the spherical-deformed shape transition. The quasi-particle vacua shell model enables us to perform shell-model calculations with sufficiently large model space with the ${}^{110}$Zr inert core. The shell-model result well reproduces the experimental excitation energies and quadrupole properties of the yrast and non-yrast states. The nuclear matrix element of neutrinoless double-beta decay of ${}^{150}$Nd is evaluated showing its modest enhancement by shape mixing.