Neutrino parameters and the $N_2$-dominated scenario of leptogenesis

TL;DR

This paper reviews leptogenesis scenarios, especially the $N_2$-dominated case, analyzing success rates, conditions for strong thermal leptogenesis, and implications for neutrino mass measurements.

Contribution

It provides a comparative analysis of flavoured and unflavoured leptogenesis models and discusses conditions favoring strong thermal leptogenesis with implications for neutrino masses.

Findings

Strong thermal leptogenesis favors $m_1\gtrsim10$ meV for normal ordering.

For inverted ordering, $m_1\gtrsim 3$ meV is favored.

Neutrino mass experiments can support or challenge strong thermal leptogenesis.

Abstract

We briefly review the main aspects of leptogenesis, describing both the unflavoured and the flavoured versions of the $N_2$-dominated scenario. A study of the success rates of both classes of models has been carried out. We comment on these results and discuss corrective effects to this simplest scenario. Focusing on the flavoured case, we consider the conditions required by strong thermal leptogenesis, where the final asymmetry is fully independent of the initial conditions. Barring strong cancellations in the seesaw formula and in the flavoured decay parameters, we show that strong thermal leptogenesis favours a lightest neutrino mass $m_1\gtrsim10\,\mbox{meV}$ for normal ordering (NO) and $m_1\gtrsim 3\,\mbox{meV}$ for inverted ordering (IO). Finally, we briefly comment on the power of absolute neutrino mass scale experiments to either support or severely corner strong thermal leptogenesis.