Phenomenology of New Physics in the Neutrino Sector

This PhD thesis covers my work done at the KIT under the supervision of Prof. Thomas Schwetz-Mangold, in the field of neutrino-oscillation phenomenology. I first give an historical overview of neutrino physics, covering the Standard Model of particle physics, how the neutrino was discovered, and the experimental developments that led to the discovery of the neutrino, and subsequent experimental developments. Then I cover the latest analysis of the three-neutrino oscillation parameters with all relevant experimental data, which was done as a part of the NuFit collaboration. The global dataset contains opposing tendencies, which have low statistical significance, but may develop into a serious tension with future exposure. Then I cover my work undertaking a statistically rigorous analysis of the sterile-neutrino hypothesis, using data from terrestrial experiments, as well as solar data with a focus on the recent claimed evidence of sterile neutrinos from the Neutrino-4 and BEST experimental collaborations. The significant statistical tensions within the datasets are also evaluated, as the solar data constrains the sterile-neutrino hypothesis. ... mehrFinally, I consider the so-called neutrino dipole portal, where a neutrino interacts with a new heavy neutral particle via a magnetic interaction. This interaction was proposed to explain an observed excess at MiniBooNE. I consider this type of interaction with the different flavours of neutrino at the future experiment DUNE, which will use new liquid-argon detector technology, which will be able to distinguish electron and photon tracks. I find that DUNE is well placed to probe the neutrino dipole portal at currently unconstrained parameter space, and will be competitive with other proposed experiments such as SHiP.