1Technical University of Munich, TUM School of Natural Sciences, Physics Department, Professorship T30d Elementary Particle Physics, James-Franck-Strasse 1, 85748 Garching, Germany,
3Instituto de Astronomía, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Apartado Postal 70-264, 04510 Ciudad México, México
4Center for Neutrino Physics, Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, USA