Göttingen 2012 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 21: Astroteilchenphysik, Kosmologie / Neutrinophysik (Theorie)
T 21.7: Vortrag
Dienstag, 28. Februar 2012, 18:15–18:30, VG 3.101
Sterile Neutrinos for Warm Dark Matter and the Reactor Anomaly in Flavor Symmetry Models — •James Barry, Werner Rodejohann, and He Zhang — Max-Planck-Institut für Kernphysik, Heidelberg, Germany
The existence of light active neutrino masses requires new physics beyond the Standard Model, with current theoretical prejudice favouring the introduction of heavy right-handed (sterile) neutrinos: the seesaw mechanism. However, there are a number of recent experimental hints, both from oscillation physics and cosmological parameter fits, that point towards the existence of light sterile neutrinos in the eV mass range. In addition, keV-scale sterile neutrinos are a prime candidate for Warm Dark Matter, whose existence could solve some of the problems of the Cold Dark Matter paradigm by reducing the number of Dwarf satellite galaxies or smoothing cusps in Dark Matter halos.
We examine the feasibility of incorporating sterile neutrinos of different mass scales into type I seesaw neutrino mass models (and effective models) with flavour symmetries, in particular a model based on the tetrahedral group A4 augmented with a Froggatt-Nielsen U(1) symmetry. Higher order seesaw terms and higher-dimensional effective operators are discussed in detail, and the phenomenological consequences for both active and active-sterile neutrino mixing as well as for neutrinoless double beta decay (0νββ) are presented. Light sterile neutrinos induce deviations from the zeroth order tri-bimaximal mixing, and can have a significant influence on the effective mass in 0νββ.