# Neutrino CP phases from Sneutrino Chaotic Inflation

## TL;DR

This paper explores how a minimal sneutrino chaotic inflation model, combined with Froggatt-Nielsen flavor symmetry, predicts specific CP-violating phases in neutrinos, linking inflationary dynamics with neutrino properties.

## Contribution

It demonstrates the impact of flavor symmetry on CP phases in a sneutrino inflation model, highlighting conditions that favor certain CP phase values and their relation to neutrino data.

## Key findings

- Dirac CP phase peaks at ±π/4 and ±3π/4 when symmetry is on stabilizer Yukawas.
- Vanishing and maximal CP phases are disfavored in certain symmetry scenarios.
- Models with symmetry on both inflaton and stabilizer Yukawas struggle to fit neutrino observations.

## Abstract

We study if the minimal sneutrino chaotic inflation is consistent with a flavor symmetry of the Froggatt-Nielsen type, to derive testable predictions on the Dirac and Majorana CP violating phases, $\delta$ and $\alpha$. For successful inflation, the two right-handed neutrinos, i.e., the inflaton and stabilizer fields, must be degenerate in mass. First we find that the lepton flavor symmetry structure becomes less manifest in the light neutrino masses in the seesaw mechanism, and this tendency becomes most prominent when right-handed neutrinos are degenerate. Secondly, the Dirac CP phase turns out to be sensitive to whether the shift symmetry breaking depends on the lepton flavor symmetry. When the flavor symmetry is imposed only on the stabilizer Yukawa couplings, distributions of the CP phases are peaked at $\delta \simeq \pm \pi/4, \pm 3\pi/4$ and $\alpha = 0$, while the vanishing and maximal Dirac CP phases are disfavored. On the other hand, when the flavor symmetry is imposed on both the inflaton and stabilizer Yukawa couplings, it is rather difficult to explain the observed neutrino data, and those parameters consistent with the observation prefer the vanishing CP phases $\delta = 0, \pi$ and $\alpha = 0$.