Abstract
In light of the latest neutrino oscillation data, we revisit the minimal scenario of type-I seesaw model, in which only two heavy right-handed Majorana neutrinos are introduced to account for both tiny neutrino masses and the baryon number asymmetry in our Universe. In this framework, we carry out a systematic study of the Frampton-Glashow-Yanagida ansatz by taking into account the renormalization-group running of neutrino mixing parameters and the flavor effects in leptogenesis. We demonstrate that the normal neutrino mass ordering is disfavored even in the minimal supersymmetric standard model with a large value of tan β, for which the running effects could be significant. Furthermore, it is pointed out that the original scenario with a hierarchical mass spectrum of heavy Majorana neutrinos contradicts with the upper bound derived from a naturalness criterion, and the resonant mechanism with nearly-degenerate heavy Majorana neutrinos can be a possible way out.
Highlights
In light of the latest neutrino oscillation data, we revisit the minimal scenario of type-I seesaw model, in which only two heavy right-handed Majorana neutrinos are introduced to account for both tiny neutrino masses and the baryon number asymmetry in our Universe
In the basis where both the charged-lepton mass matrix Ml = diag{me, mμ, mτ } and the mass matrix of heavy Majorana neutrinos MR = diag{M1, M2, M3} ≡ MR are diagonal, the neutrino mass spectrum and lepton flavor mixing are determined by the effective neutrino mass matrix Mν = −MDMR−1MDT, which can be diagonalized as Mν = U · diag{m1, m2, m3} · U T with U being the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix [7,8,9]
It has been demonstrated that discrete flavor symmetries can be implemented to successfully predict interesting lepton flavor mixing patterns, which are well compatible with the latest neutrino oscillation data
Summary
We start with neutrino mass spectrum and flavor mixing parameters in the type-I seesaw model with only two right-handed heavy Majorana neutrinos. We proceed to introduce the FGY ansatz and explore its phenomenological implications. The RG evolution of neutrino masses and mixing parameters is considered when we confront the FGY ansatz with low-energy neutrino oscillation data. The model parameters relevant for leptogenesis at the high-energy scale are determined
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
