Caroline Fengler (KIT)

Chasing the cat's tail? - Hidden signatures of the neutrino mass and new physics in tritium β decay at KATRIN

Abstract: 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, such as light sterile neutrinos, Lorentz invariance violation and local relic neutrinos. 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. First constraints on these novel interactions have been derived based on the data of the second measurement campaign. This talk will highlight the most recent KATRIN neutrino mass results based on the first five measurement campaigns. Furthermore, the latest status of the Beyond the Neutrino Mass searches will be presented, with a focus on the search for generalised neutrino interactions.