Tri-bimaximal neutrino mixing and flavor-dependent resonant leptogenesis

Abstract

We propose a particularly economical neutrino mass model, in which there are only two right-handed Majorana neutrinos of O ( 1 ) TeV and their masses are highly degenerate. Its novel Yukawa-coupling texture together with the seesaw mechanism allows us to achieve the normal neutrino mass hierarchy with m 1 = 0 and a nearly tri-bimaximal neutrino mixing pattern with the maximal CP-violating phase: θ 23 = π / 4 , | δ | = π / 2 and sin 2 θ 12 = ( 1 − 2 tan 2 θ 13 ) / 3 . One may also obtain the inverted neutrino mass hierarchy with m 3 = 0 and the corresponding neutrino mixing pattern with θ 23 = π / 4 and θ 13 = δ = 0 . In both cases, it is possible to interpret the cosmological baryon number asymmetry η B ≈ 6.1 × 10 −10 through the resonant leptogenesis mechanism. We demonstrate the significance of flavor-dependent effects in this leptogenesis scenario: they can either flip the sign of the flavor-independent prediction for η B in the m 1 = 0 case or magnify the magnitude of the flavor-independent prediction for η B about 50 times in the m 3 = 0 case.