Physics

Prof. Amitava Raychaudhuri
University of Kolkata

Abstract:

Neutrino oscillation results have given us a picture of their masses and mixing. Unlike in the quark sector, some mixing angles in the lepton sector are large. However, this is not the complete story.  There are several small quantities too. For example θ₁₃ is small compared to θ₁₂ and θ₂₃, the deviation of θ₂₃ from p/4 is small, and the solar mass splitting is two orders smaller than the atmospheric one. We propose a model with an A4 flavour symmetry in which the neutrino mass matrix emerges from two see-saw steps. In the first, all the small quantities noted above are zero. The second step generates the non-zero values for all of them and in the process leads to testable interrelationships. The model can be falsified in the ongoing and upcoming experiments.