Neutrinoless double beta decay ofCa48

The neutrinoless double beta decay of ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ is studied in a shell-model framework. Inclusion of the recoil terms in the hadronic currents is found to be essential in giving the right order of magnitude for the coupling constant between left and right currents. Short-range correlations and nucleon-size effects are also examined. The comparison of calculations in the full and truncated pf shell spaces indicates that the process is not very sensitive to nuclear-structure details. Assuming a mass of 1 eV for the electron neutrino the calculated half-life for the (${\mathrm{\beta }}^{\mathrm{-}}$ ${\mathrm{\beta }}^{\mathrm{-}}$ ${)}_{0\nu }$ mode is ${\mathit{T}}_{1/2}^{(0\mathrm{}\nu )}$≃${10}^{25}$ yr.