Summer school

I gave a lecture at summer school for graduate students in particle physics. I uploaded the slides. There were many questions and I enjoyed the school.

A new paper

My new paper on the neutrino CP phases appeared on arXiv today.

We imposed a simple FN flavor symmetry on the lepton sector in the minimal sneutrino chaotic inflation where the number of right-handed neutrinos are two. It turned out that the Dirac CP phase is sensitive to whether the inflaton Yukawa couplings, which break the shift symmetry explicitly, depend on the lepton flavor symmetry. The Dirac CP phases around delta = -pi/4, -3pi/4 are favored, which can be checked by future neutrino experiments!

What I found interesting is that, in general, the flavor symmetry structure is less obvious in the (light) neutrino mass matrix in the seesaw mechanism, because some cancellation often occurs in the seesaw formula. As a result, the mixing angles are shifted to smaller values, compared to naively expected ones based on the imposed flavor structure.