Physics with beam tau-neutrino appearance at DUNE

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) -> nu(tau)) at thorn 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 nu(e)-appearance 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 nonunitary lepton mixing matrix, the 3 + 1 light neutrinos hypothesis, and the existence of nonstandard 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.