The Half-Life and the Nuclear Matrix Element of the $2\nu\beta\beta$   Decay in $^{76}Ge$
  We apply the shell-model wave-functions of $^{76}Ge$ to calculate the nuclear matrix elements and the half-life of the $2\nu\beta\beta$ decay in $^{76}Ge$. Our result is comparable to the recent observed $2\nu\beta\beta$-decay half-life of $^{76}Ge$. Furthemore it provides the upper limit of the effective neutrino mass is about 0.4 eV from the recent experimental data of the $0\nu\beta\beta$-decay half-life. 
Hui-fang Wu and Tao Huang