(beta beta)_{0 nu}-decay: a possible test of the nuclear matrix element   calculations
  The existing calculations of the nuclear matrix elements of the neutrinoless double beta-decay differ by about a factor three. This uncertainty prevents quantative interpretation of the results of experiments searching for this process. We suggest here that the observation of the neutrinoless double beta-decay of several nuclei in future experiments of could allow to test different calculations of the nuclear matrix elements through the direct comparison of them with the experimental data. 
S.M. Bilenky and J.A. Grifols