A dynamical approach to link low energy phases with leptogenesis

Abstract

If lepton masses and mixings are explained by a flavour symmetry in seesaw model which leads to U_{e3}=0 at leading order, we find that, under reasonable assumptions, a future observation of low energy leptonic CP violation implies, barring accidental cancellations, a lepton asymmetry both in flavoured leptogenesis and in its one-flavour approximation. We explicitly implement this approach with a predictive seesaw model for Tri-Bimaximal Mixing (TBM) and show how cosmological baryon asymmetry can be directly trigged by low energy phases appearing in $U_{e3}$. Thanks to this direct correlation we can derive a lower bound on the reactor angle \theta_{13}: \sin^2 \theta_{13} \gtrsim 0.005.

Comments: 5 pages, A4 model example revised with a larger abelian factor, typos corrected, references added