Precision neutrino experiments vs the Littlest Seesaw

TL;DR

This paper evaluates how upcoming precision neutrino experiments can test and potentially exclude the Littlest Seesaw model, which predicts neutrino masses and mixing with high accuracy, by analyzing experimental sensitivities and parameter correlations.

Contribution

It provides a comprehensive assessment of the Littlest Seesaw model's testability with future experiments, highlighting the importance of combined measurements for model exclusion.

Findings

Current data fit the model well with specific predictions.

Future experiments can test key parameters like atmospheric and solar angles.

Excluding the model requires a combined analysis of multiple experimental results.

Abstract

We study to what extent upcoming precision neutrino oscillation experiments will be able to exclude one of the most predictive models of neutrino mass and mixing: the Littlest Seesaw. We show that this model provides a good fit to current data, predicting eight observables from two input parameters, and provide new assessments of its predictions and their correlations. We then assess the ability to exclude this model using simulations of upcoming neutrino oscillation experiments including the medium-distance reactor experiments JUNO and RENO-50 and the long-baseline accelerator experiments DUNE and T2HK. We find that an accurate determination of the currently least well measured parameters, namely the atmospheric and solar angles and the CP phase $\delta$, provide crucial independent tests of the model. For $\theta_{13}$ and the two mass-squared differences, however, the model's exclusion requires a combination of measurements coming from a varied experimental programme. Our results show that the synergy and complementarity of future experiments will play a vital role in efficiently discriminating between predictive models of neutrino flavour, and hence, towards advancing our understanding of neutrino oscillations in the context of the flavour puzzle of the Standard Model.