Beta-Decay Spectrum and Lorentz Violation

Relativity theory and its underlying Lorentz and CPT invariance represent key principles of physics and therefore require continued experimental scrutiny across the broadest possible range of energy scales and physical systems. Possibilities for tests of these symmetries in precision $\beta$-decay experiments with focus on KATRIN are investigated. It is found that countershaded departures from relativity, which represent a particular challenge to detection, are accessible in such experiments. In this context, it is argued that KATRIN would be in an excellent position to conduct the first-ever experimental search for countershaded Lorentz and CPT breaking in neutrinos.