Nuclear matrix elements for $0νββ$ decay with improved short‐range correlations

Nuclear matrix elements for the neutrinoless double beta minus $(0νβ−β−)$ decays of all interesting (nearly) spherical nuclei are calculated for the light‐neutrino exchange mechanism by using the proton‐neutron quasiparticle random‐phase approximation (pnQRPA) with a realistic nucleon‐nucleon force. The finite size of a nucleon, the higher‐order terms of nucleonic weak currents, and the nucleon‐nucleon short‐range correlations (s.r.c) are taken into account. The s.r.c. are computed by the use of the unitary correlation operator method (UCOM), superior to the traditional Jastrow method. The UCOM computed matrix elements turn out to be considerably larger than the Jastrow computed ones.