Union of rotational and vibrational modes in generator-coordinate-type calculations, with application to neutrinoless double-β decay
Good many-body methods for medium and heavy nuclei are important. Here we combine rotational motion with vibrational modes in a novel generator-coordinate method (GCM): starting from a mean-field solution (Hartree-Fock-Bogoliubov), we create nonorthogonal reference states from low-lying quasiparticle Tamm-Dancoff modes, and then project onto states of good angular momentum and particle number. Here, the results we benchmark against full shell model calculations. Even with just a few such modes we find improvement over standard GCM calculations in excitation spectra. We also find significant improvement in 0νββ nuclear matrix elements.