The Effective Description of General Neutrino Interactions in Tritium β Decay and first Constraints based on the second KATRIN Science Run

The KArlsuhe TRItium Neutrino experiment (KATRIN) aims to measure the effective electron anti-neutrino mass by precision spectroscopy of tritium β decay. With a data set of 259 measurement days and optimised experimental conditions, KATRIN recently set a new world-leading constraint on the neutrino mass from direct kinematic measurement, with a 0.45 eV/c² sensitivity.
Beyond the neutrino mass, the ultra-precise measurement of the β spectrum at KATRIN can reveal further distinct signatures of new physics. To cover multiple new physics scenarios, the so-called generalised neutrino interactions are incorporated into the β-spectrum model; their contributions to the weak interaction can be identified by unique energy-dependent modifications of the measured spectrum in KATRIN. In this thesis, first constraints on these novel interactions are derived based on the data of the second measurement campaign and future prospects on the sensitivity of the final KATRIN data set and on the impact of the upcoming TRISTAN detector upgrade are given.