A study on a minimally broken residual TBM-Klein symmetry with its implications on flavoured leptogenesis and ultra high energy neutrino flux ratios

Understand

We present a systematic study on minimally perturbed neutrino mass matrices which at the leading order give rise to Tri-BiMaximal (TBM) mixing due to a residual $\mathbb{Z}_2\times \mathbb{Z}_2^{\mu\tau}$ Klein symmetry in the neutrino mass term of the low energy effective seesaw Lagrangian.

• Considering only the breaking of $\mathbb{Z}_2^{\mu\tau}$ with two relevant breaking parameters ($\epsilon_{4,6}^\prime$), after a comprehensive numerical analysis, we show that the phenomenologically viable case in this scenario is a special case of TM1 mixing.
• For this class of models, from the phenomenological perspective, one always needs large breaking (more than $ 45\%$) in one of the breaking parameters.
• However, to be consistent the maximal mixing of $\theta_{23}$, while more than $ 35\%$ breaking is needed in the other, a range $49.4^\circ-53^\circ$ and $38^\circ-40^\circ$ could be probed allowing breaking up to $ 25\%$ in the same parameter.