Toward verifying leptonic unitarity

After briefly mentioning that measurement of the neutrino parameters may have more bright feature than it was thought, I ask the question “what would be the way to conclude these neutrino endeavour?”. Of course, the final goal is to understand the origin of the neutrino (and fermion) masses, but related to this, the completeness of the framework has to be checked before concluding the story. That is, verifying leptonic unitarity. I hope I will deliver some thoughts on how to carry this out. I will start by considering the method of unitarity triangle (which is hard) but eventually goes into more model dependent ways. I will contrast high-scale unitarity violation with low-scale one. A struggle to construct “model-independent framework of low-scale unitarity violation" is described.