Spin-dipole nuclear matrix element for the double beta decay of Ge-76 by the (He-3, t) charge-exchange reaction

摘要

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) J(pi) = 2(-) NME is one of the major components associated with the DBD NME. The SD NME for Ge-76 was derived for the first time by using the (74,76) Ge (He-3, t) at RCNP Osaka. The obtained SD NME for the Ge-76 -> As-76 ground-state transition is divide M EXP-(SD) ivide = 1.5 x 10-3 k 0.2 with respect to the quasi-particle model NME divide MQP-(SD) divide