# Study of a tri-direct littlest seesaw model at MOMENT

## TL;DR

This paper evaluates how the MOMENT neutrino experiment can test and refine the tri-direct littlest seesaw (TDLS) model, highlighting its potential to exclude the model and improve parameter precision.

## Contribution

The study analyzes the impact of MOMENT on the TDLS model, demonstrating its ability to exclude the model at high confidence and enhance parameter measurement accuracy.

## Key findings

- MOMENT can exclude the TDLS model at over 5σ if current best-fit values are confirmed.
- MOMENT improves the 3σ precision of model parameters by at least a factor of two.
- The experiment can observe the predicted sum rule between heta_{23} and \delta$.

## Abstract

The flavour symmetry succeeds in explaining the current global fit results. Flavour-symmetry models can be tested by the future experiments that improve the precision of neutrino oscillation parameters, \textit{such as} the MuOn-decay MEdium baseline NeuTrino beam experiment (MOMENT). In this work, we consider tri-direct littlest seesaw (TDLS) models for a case study, and analyze how much MOMENT can extend our knowledge on the TDLS model. We find that measurements of $\theta_{23}$ and $\delta$ are crucial for MOMENT to exclude the model at more than $5\sigma$ confidence level, if the best fit values in the last global analysis result is confirmed. Moreover, the $3\sigma$ precision of model parameters can be improved at MOMENT by at least a factor of two. Finally, we project the surface at the $3\sigma$ confidence level from the model-parameter space to the oscillation-parameter space, and find the potential of MOMENT to observe the sum rule between $\theta_{23}$ and $\delta$ predicted by TDLS.