# Golden Littlest Seesaw

## TL;DR

This paper introduces a new class of Littlest Seesaw models based on the Golden Ratio mixing, analyzing their symmetry properties, vacuum alignments, and compatibility with neutrino data, providing extensive benchmarks and comparisons.

## Contribution

It presents a novel Littlest Seesaw framework with specific symmetry-based vacuum alignments linked to the Golden Ratio, expanding the landscape of neutrino mass models.

## Key findings

- Identifies viable vacuum alignments consistent with $A_5$ symmetry.
- Provides benchmark points matching neutrino oscillation data.
- Shows compatibility of new models with recent global neutrino analyses.

## Abstract

We propose and analyse a new class of Littlest Seesaw models, with two right-handed neutrinos in their diagonal mass basis, based on preserving the first column of the Golden Ratio mixing matrix. We perform an exhaustive analysis of all possible remnant symmetries of the group $A_5$ which can be used to enforce various vacuum alignments for the flavon controlling solar mixing, for two simple cases of the atmospheric flavon vacuum alignment. The solar and atmospheric flavon vacuum alignments are enforced by {\em different} remnant symmetries. We examine the phenomenological viability of each of the possible Littlest Seesaw alignments in $A_5$, which preserve the first column of the Golden ratio mixing matrix, using figures and extensive tables of benchmark points and comparing our predictions to a recent global analysis of neutrino data. We also repeat the analysis for an alternative form of Golden Ratio mixing matrix.