# Physics with Beam Tau-Neutrino Appearance at DUNE

## TL;DR

This paper assesses DUNE's potential to measure tau-neutrino interactions, testing the three-neutrino paradigm and exploring new physics hypotheses through tau appearance data.

## Contribution

It demonstrates DUNE's capability to significantly enhance tau-neutrino detection and use this data to probe beyond-standard-model neutrino physics.

## Key findings

- DUNE can identify more tau-neutrino events than existing experiments.
- Tau appearance data can test the three-massive-neutrinos paradigm.
- Sensitivity to non-standard neutrino interactions is improved.

## Abstract

We explore the capabilities of the upcoming Deep Underground Neutrino Experiment (DUNE) to measure $\nu_\tau$ charged-current interactions and the associated oscillation probability $P(\nu_\mu \to \nu_\tau)$ at its far detector, concentrating on how such results can be used to probe neutrino properties and interactions. DUNE has the potential to identify significantly more $\nu_\tau$ events than all existing experiments and can use this data sample to nontrivially test the three-massive-neutrinos paradigm by providing complementary measurements to those from the $\nu_e$ appearance and $\nu_\mu$ disappearance channels. We further discuss the sensitivity of the $\nu_\tau$ appearance channel to several hypotheses for the physics that may lurk beyond the three-massive-neutrinos paradigm: a non-unitary lepton mixing matrix, the $3+1$ light neutrinos hypothesis, and the existence of non-standard neutral-current neutrino interactions. Throughout, we also consider the relative benefits of the proposed high-energy tune of the Long-Baseline Neutrino Facility (LBNF) beam-line.