Flavoured leptogenesis and ${\rm CP}^{\mu\tau}$ symmetry

Understand

We present a systematic study of leptogenesis in neutrino mass models with $\mu\tau$-flavoured CP symmetry.

• In addition to the strong hierarchical $N_1$-dominated scenario ($N_1$DS) in the `two flavour regime' of leptogenesis, we show that one may choose the right-handed (RH) neutrino mass hierarchy as mild as $M_2\simeq 4.7 M_1$ for a perfectly valid hierarchical $N_1$DS.
• This in turn reduces the lower bound on the allowed values of $M_1$, compared to what is stated in the literature.
• The consideration of flavour effects due to the heavy neutrinos also translate into an upper bound on $M_1$.