Allowed region for the (second) lightest mass $M_{1,2}$ of right-handed neutrino $\hat{I}{½}_{R1,2}$ with $SO(10)$-inspired relations and sequential dominance

Masaki J. S. Yang

In this paper, we evaluate the (second) lightest mass $M_{1,2}$ of right-handed neutrino $\hat{I}{½}_{R1,2}$ in grand unified theories with the type-I seesaw mechanism that predicts an alm…