Efficient QRPA calculation for two-neutrino double-beta decay nuclear matrix element

A formulation for calculating the double Gamow-Teller transition and two-neutrino double-beta decay nuclear matrix elements based on the linear response for nuclear density functional theory is presented. The matrix elements are expressed as double contour integration in the complex-energy plane. Test calculations for 48Ca double Gamow-Teller transition and 2νββ decay are performed in order to show the feasibility of this new approach.A formulation for calculating the double Gamow-Teller transition and two-neutrino double-beta decay nuclear matrix elements based on the linear response for nuclear density functional theory is presented. The matrix elements are expressed as double contour integration in the complex-energy plane. Test calculations for 48Ca double Gamow-Teller transition and 2νββ decay are performed in order to show the feasibility of this new approach.