SMMC method for two-neutrino double beta decay

Abstract

Shell Model Monte Carlo (SMMC) techniques are used to calculate two-neutrino double beta decay matrix elements. We validate the approach against direct diagonalization for ${}^{48}$Ca in the complete $pf$-shell using the KB3 interaction. The method is then applied to the decay of ${}^{76}$Ge in the $(0f_{5/2},1p,0g_{9/2})$ model space using a newly calculated realistic interaction. Our result for the matrix element is $0.13\pm 0.05$ MeV${}^{-1}$, in agreement with the experimental value.

10 pages, 3 figures available at http://www.krl.caltech.edu/preprints/MAP.html