Aiming to relate leptonic CP violating phase δ to the cosmological CP asymmetry, we study the extension of MSSM by two quasi-degenerate (strictly degenerate at tree level) righthanded neutrinos and consider all possible two texture zero 3 × 2 Yukawa matrices plus one ∆L = 2 dimension five (d = 5) operator contributing to the light neutrino mass matrix. We classify all experimentally viable mass matrices, leading to several predictions, and analytically derive predictive relations. We also relate the CP violating δ phase to the CP phase of the thermal leptogenesis.

Within the extension of MSSM by two right handed neutrinos, which masses are degenerate at tree level, we address the issue of leptogenesis. Investigating the quantum corrections in details, we show that the lepton asymmetry is induced at 1-loop level and decisive role is played by the tau lepton Yukawa coupling. On a concrete and predictive neutrino model, which enables to predict the CP violating δ phase and relate it to the cosmological CP asymmetry, we demonstrate that the needed amount of the baryon asymmetry is generated via the resonant leptogenesis.

Within the low scale resonant leptogenesis scenario, the cosmological CP asymmetry may arise by radiative corrections through the charged lepton Yukawa couplings. While in some cases, as one expects, decisive role is played by the λ τ coupling, we show that in specific neutrino textures only by inclusion of the λ µ the cosmological CP violation is generated at 1-loop level.With the purpose to relate the cosmological CP violation to the leptonic CP phase δ, we consider an extension of MSSM with two right handed neutrinos (RHN), which are degenerate in mass at high scales. Together with this, we first consider two texture zero 3×2 Dirac Yukawa matrices of neutrinos. These via see-saw generated neutrino mass matrices augmented by single ∆L = 2 dimension five (d = 5) operator give predictive neutrino sectors with calculable CP asymmetries. The latter is generated through λ µ,τ coupling(s) at 1-loop level. Detailed analysis of the leptogenesis is performed. We also revise some one texture zero Dirac Yukawa matrices, considered earlier, and show that addition of a single ∆L = 2, d = 5 entry in the neutrino mass matrices, together with newly computed 1-loop corrections to the CP asymmetries, give nice accommodation of the neutrino sector and desirable amount of the baryon asymmetry via the resonant leptogenesis even for rather low RHN masses(∼few TeV -10 7 GeV).

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