Leptogenesis in \u0394(27) with a universal texture zero

Abstract

We investigate the possibility of viable leptogenesis in an appealing Δ(27) model with a universal texture zero in the (1,1) entry. The model accommodates the mass spectrum, mixing and CP phases for both quarks and leptons and allows for grand unification. Flavoured Boltzmann equations for the lepton asymmetries are solved numerically, taking into account both N1 and N2 right-handed neutrino decays. The N1-dominated scenario is successful and the most natural option for the model, with M1 ∈ [109, 1012] GeV, and M1/M2 ∈ [0.002, 0.1], which constrains the parameter space of the underlying model and yields lower bounds on the respective Yukawa couplings. Viable leptogenesis is also possible in the N2-dominated scenario, with the asymmetry in the electron flavour protected from N1 washout by the texture zero. However, this occurs in a region of parameter space which has a stronger mass hierarchy M1/M2< 0.002, and M2 relatively close to M3, which is not a natural expectation of the Δ(27) model.