On the Neutrino Mass Spectrum and Neutrinoless Double-Beta Decay

Assuming 3-neutrino mixing, neutrino oscillation explanation of the solar and atmospheric neutrino data, massive Majorana neutrinos and neutrinoless double beta-decay generated only by the (V-A) charged current weak interaction via the exchange of the three Majorana neutrinos, we analyze in detail the possibility of determining the type of the neutrino mass spectrum by measuring of the effective Majorana mass || in neutrinoless double-beta decay. The three possible types of neutrino mass spectrum are considered: i) with normal hierarchy (NH) m1 | due to the imprecise knowledge of the relevant nuclear matrix elements. We derive the ranges of values of the mixing angle which controls the solar neutrino oscillations for which the measurement of || would allow one to discriminate between the NH and IH, NH and QD and IH and QD spectra. The requirements which the possibility of distinguishing between the three types of spectra imposes on the uncertainty in the values of the neutrinoless double beta-decay nuclear matrix elements, are also determined