Bridges of Low Energy observables with Leptogenesis in μ − τ Reflection Symmetry

X iv :0 81 1. 14 58 v1 [ he pph ] 1 0 N ov 2 00 8 Bridges of Low Energy observables with Leptogenesis in μ− τ Reflection Symmetry Y. H. Ahn, Sin Kyu Kang, C. S. Kim, T. Phong Nguyen a Institute of Physics, Academia Sinica, Taipei, Taiwan 115, ROC b School of Liberal Arts, Seoul National Univ. of Technology, Seoul 139-743, Korea c Dept. of Physics and IPAP, Yonsei University, Seoul 120-749, Korea Abstract We consider an exact μ − τ reflection symmetry in neutrino sector realized at the GUT scale in the context of the seesaw model with and without supersymmetry. Assuming the two lighter heavy Majorana neutrinos are degenerate at the GUT scale, it is shown that the renormalization group (RG) evolution from the GUT scale to the seesaw scale gives rise to breaking of the μ − τ symmetry and a tiny splitting between two degenerate heavy Majorana neutrino masses as well as small variations of the CP phases in Yν , which are essential to achieve a successful leptogenesis. Such small RG effects lead to tiny deviations of θ23 from the maximal value and the CP phase δCP from π2 imposed at the GUT scale due to μ− τ reflection symmetry. In our scenario, the required amount of the baryon asymmetry ηB can be generated via so-called resonant e-leptogenesis, in which the wash-out factor concerned with electron flavor plays a crucial role in reproducing a successful leptogenesis. We show that CP violation responsible for the generation of baryon asymmetry of our universe can be directly linked with CP violation measurable through neutrino oscillation as well as neutrino mixing angles θ12 and θ13. We expect that, in addition to the reactor and long baseline neutrino experiments, the measurements for the supersymmetric parameter tan β at future collider experiments would serve as an indirect test of our scenario of baryogenesis based on the μ− τ reflection symmetry.