Improved short-range correlations and0νββnuclear matrix elements ofGe76andSe82

Abstract

We calculate the nuclear matrix elements of the neutrinoless double beta ($0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$) decays of $^{76}\mathrm{Ge}$ and $^{82}\mathrm{Se}$ for the light neutrino exchange mechanism. The nuclear wave functions are obtained by using realistic two-body forces within the proton-neutron quasiparticle random-phase approximation (pnQRPA). We include the effects that come from the finite size of a nucleon, from the higher-order terms of nucleonic weak currents, and from the nucleon-nucleon short-range correlations. Most importantly, we improve on the presently available calculations by replacing the rudimentary Jastrow short-range correlations by the more advanced unitary correlation operator method (UCOM). The UCOM-corrected matrix elements turn out to be notably larger in magnitude than the Jastrow-corrected ones. This has drastic consequences for the detectability of $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ decay in present and future double beta experiments.