Two-neutrino double-β decay matrix elements based on a relativistic nuclear energy density functional

Nuclear matrix elements (NMEs) for two-neutrino double- decay (2) are studied in the framework of a relativistic nuclear energy density functional. The properties of nuclei involved in the decay are obtained using the relativistic Hartree-Bardeen-Cooper-Schrieffer theory and relevant nuclear transitions are described using the relativistic proton-neutron quasiparticle random phase approximation based on the relativistic energy density functional. Three effective interactions are employed, including density-dependent meson-exchange (DD-ME2) and point-coupling interactions (DD-PC1 and DD-PCX), and pairing correlations are described consistently both in T=1 and T=0 channels using a separable pairing interaction. The optimal values of T=0 pairing strength parameter V₀₏₏ are constrained by the experimental data on -decay half-lives. The 2 matrix elements and half-lives are calculated for several nuclides experimentally known to undergo this kind of decay: ^48Ca, ^76Ge, ^82Se, ^96Zr, ^100Mo, ^116Cd, ^124Xe, ^128Te, ^130Te, ^136Xe, and ^150Nd. The model dependence of the NMEs and their sensitivity on V₀₏₏ is investigated, and the NMEs obtained using optimal values of V₀₏₏ are discussed in comparison to previous studies. The results of the present work represent an important benchmark for the future applications of the relativistic framework in studies of neutrinoless double- decay.