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Nuclear matrix elements (NMEs) for double beta decays (DBDs) are crucial for studying the neutrino mass and other neutrino properties beyond the standard electro-weak model by measuring neutrino-less DBDs. The spin-dipole (SD) Jπ = 2− NME is one of the major components associated with the DBD NME. The SD NME for 76Ge was derived for the first time by using the 74,76 Ge (3He, t) at RCNP Osaka. The obtained SD NME for the 76Ge → 76As ground-state transition is in natural units. This is smaller by a coefficient around k ≈ 0.2 with respect to the quasi-particle model NME. The impact of the reduced (quenched) SD NME on DBD neutrino studies is discussed. [ABSTRACT FROM AUTHOR]

The Gamow–Teller strength distributions of 116 Sb and 122 Sb were measured with the 116 , 122 Sn (3 He , t) 116 , 122 Sb charge-exchange reactions at 140 MeV/u . The measurements were carried out at the Research Center for Nuclear Physics (RCNP) at Osaka University in Osaka, Japan using the Grand Raiden spectrometer. The data were analysed by Multipole-Decomposition Analysis (MDA). The Gamow–Teller strengths summed up to 28 MeV are (38 ± 7) % and (48 ± 6) % of the Ikeda sum rule for 116 Sb and 122 Sb , respectively, if the quasi-free scattering (QFS) contribution is not subtracted. These percentages are (29 ± 7) % and (35 ± 5) % , respectively, if the QFS contribution is maximally subtracted. These results were compared to those from previous measurements of the same isotopes, to recent measurements of 150 Pm , and to a Quasi-particle Random-Phase Approximation (QRPA) calculation with Quasi-Particle Vibration Coupling (QPVC). The data suggest that the true QFS contribution is small for 116 Sb , but are inconclusive about whether the QFS contribution is small or significant for 122 Sb . Therefore, these data may provide an interesting test for the general quenching phenomenon of the Gamow–Teller Resonance (GTR). However, more research to reveal the nature of the QFS contribution is still needed on both the experimental and the theoretical side. [ABSTRACT FROM AUTHOR]