# Littlest Inverse Seesaw Model

## TL;DR

This paper introduces a minimal inverse seesaw model with an $S_{4}$ symmetry that accurately predicts neutrino parameters and allows observable charged lepton flavor violation, differing from the traditional Littlest Seesaw.

## Contribution

The paper presents a novel inverse seesaw model based on $S_{4}$ symmetry that matches the Littlest Seesaw's neutrino predictions while enabling detectable CLFV processes.

## Key findings

- Accurately fits low energy neutrino parameters
- Predicts normal neutrino mass ordering
- Allows CLFV processes within experimental reach

## Abstract

We propose a minimal predictive inverse seesaw model based on two right-handed neutrinos and two additional singlets, leading to the same low energy neutrino mass matrix as in the Littlest Seesaw (LS) (type I) model. In order to implement such a Littlest Inverse Seesaw (LIS) model, we have used an $S_{4}$ family symmetry, together with other various symmetries, flavons and driving fields. The resulting LIS model leads to an excellent fit to the low energy neutrino parameters, including the prediction of a normal neutrino mass ordering, exactly as in the usual LS model. However, unlike the LS model, the LIS model allows charged lepton flavour violating (CLFV) processes and lepton conversion in nuclei within reach of the forthcoming experiments.