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T: Fachverband Teilchenphysik
T 20: Neutrinophysik (Theorie)
T 20.1: Talk
Monday, March 28, 2011, 16:45–17:00, 30.23: 3-1
sin2 θ12 and 0νββ–decay: Excluding the inverted neutrino–mass hierarchy — •Alexander Dueck — Max-Planck-Institut für Kernphysik, Postfach 103980, D-69029 Heidelberg, Germany
The observation of 0νββ–decay would establish the nature of the neutrino as a Majorana particle. Furthermore, the 0νββ–decay rate, or limits on it, will provide information about the absolute neutrino–mass scale and possibly determine the neutrino mass hierarchy. To convert experimental half–lifes to an effective electron neutrino mass mν, one needs to know the nuclear matrix elements (NME) of the considered decay. After reviewing how to get half–lifes from NMEs we point out the difficulties which can arise thereby and present NME values from different calculations. We scaled these NMEs to make them directly comparable.
But also of great importance is knowledge of the neutrino mixing parameters. We examine the influence of the solar neutrino mixing angle θ12 on the prospects to exclude the inverted neutrino–mass hierarchy by 0νββ–decay experiments and emphasize that a better knowledge of sin2 θ12 is desirable. Predictions for the half–life sensitivity which is needed to exclude the IH are shown for different 0νββ–decay candidate isotopes. NMEs from the Nuclear Shell Model, the Quasiparticle Random Phase Approximation, and the Interacting Boson Model are used and the half–lifes obtained for different values of the solar neutrino mixing angle θ12 are compared.