Fermi surface quasi particle model nuclear matrix elements for two neutrino double beta decays
Nuclear matrix elements (NMEs ) for two neutrino double beta decays (DBDs) are discussed in terms of the Fermi surface quasi particle model (FSQP). The NMEs for ground-state-to-ground-state DBDs depend on the Fermi surface shell configuration and the nuclear core polarization. The evaluated NMEs reproduce well the observed NMEs for decays. The NMEs for the 2ν DBDs of 78Kr, 106Cd, 130Ba and 110Pd are evaluated on the basis of FSQP. The dependence of and on the shell configuration is found to be seen in theoretical NMEs for neutrinoless DBDs. Impacts of on NMEs and experiments are discussed.