Nuclear matrix elements of neutrinoless double-$β$ decay in the triaxial projected shell model

Abstract

The nuclear matrix elements of neutrinoless double-β decay for nuclei 76 Ge, 82 Se, 100 Mo, 130 Te, and 150 Nd are studied within the triaxial projected shell model, which incorporates simultaneously the triaxial deformation and quasiparticle configuration mixing. The low-lying spectra and the B(E2 : 0 + → 2 + ) values are reproduced well. The effects of the quasiparticles configuration mixing, the triaxial deformation, and the closure approximation on the nuclear matrix elements are studied in detail. For nuclei 76 Ge, 82 Se, 100 Mo, 130 Te, and 150 Nd, the nuclear matrix elements are respectively reduced by the quasiparticle configuration mixing by 6%, 7%, 2%, 3%, and 4%, and enhanced by the odd-odd intermediate states by 7%, 4%, 11%, 20%, and 14%. Varying the triaxial deformation γ from 0 • to 60 • for the mother and daughter nuclei, the nuclear matrix elements change by 41%, 17%, 68%, 14%, and 511% respectively for 76 Ge, 82 Se, 100 Mo, 130 Te, and 150 Nd, which indicates the importance of treating the triaxial deformation consistently in calculating the nuclear matrix elements.