Texture zero neutrino models and their connection with resonant leptogenesis

Abstract

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).

The minimal seesaw and leptogenesis models

“…We proceed to discuss an appealing scenario that the extremely small mass splitting between M 1 and M 2 needed for realizing the low-scale resonant leptogenesis scenario is due to the RGE running effects [170,171,172,173,174,175]. At a superhigh scale Λ (such as the GUT scale) where the heavy Majorana neutrino masses are generated, N 1 and N 2 are assumed to possess the exactly degenerate masses; namely, M 1 = M 2 ≡ M 0 < Λ.…”

The minimal seesaw and leptogenesis models

“…We proceed to discuss an appealing scenario that the extremely small mass splitting between M 1 and M 2 needed for realizing the low-scale resonant leptogenesis scenario is due to the RGE running effects [172][173][174][175][176][177]. At a superhigh scale Λ (such as the GUT scale) where the heavy Majorana neutrino masses are generated, N 1 and N 2 are assumed to possess the exactly degenerate masses; namely, M 1 = M 2 ≡ M 0 < Λ.…”

New approach to neutrino masses and leptogenesis with Occam’s razor

“…Several approaches have been proposed to explain neutrino data [11], being the two RH neutrino extension of the SM (2RHνSM) [12,13] a framework often considered [14][15][16][17][18][19][20][21], also in the context of leptogenesis [22][23][24][25][26][27][28][29][30][31][32][33]. Following the Occam's razor spirit, previous studies have shown that the 2RHνSM with texture-zero Yukawa and mass matrices is not compatible with data for a NO spectrum [3,[34][35][36][37][38][39].…”