In this talk, we first give a brief review of the so-called minimal seesaw models and then concentrate on the minimal type-I seesaw model with two almost degenerate right-handed Majorana neutrinos of [Formula: see text]. A specific texture of the neutrino Yukawa coupling matrix is proposed to achieve the nearly tri-bimaximal neutrino mixing pattern. This ansatz predicts (1) θ23 = π/4, |δ| = π/2 and sin 2θ12 = (1 − 2tan2θ13)/3 in the m1 = 0 case; and (2) θ23 = π/4 and θ13 = 8 = 0 in the m3 = 0 case. In both cases, the cosmological baryon number asymmetry can be explained via the resonant leptogenesis mechanism. Finally, we demonstrate the significance of flavor-dependent effects in our leptogenesis scenario.
Compatibility of θ 13 and the Type I seesaw model with A 4 symmetry