Some extensions of the Standard Model of Particle Physics allow for Lorentz invariance and Charge-Parity-Time (CPT)-invariance violations. In the neutrino sector strong constraints have been set by neutrino-oscillation and time-of-flight experiments. However, some Lorentz-invariance-violating parameters are not accessible via these probes. In this work, we focus on the parameters $(a_{ \text{ of}}^{ (3)})_{ 00}$, $(a_{ \text{ of}}^{ (3)})_{ 10}$ and $(a_{ \text{ of}}^{ (3)})_{ 11}$ which would manifest themselves in a non-isotropic beta-decaying source as a sidereal oscillation and an overall shift of the spectral endpoint. Based on the data of the first scientific run of the KATRIN experiment, we set the first limit on $\left|(a_{ \text{ of}}^{ (3)})_{ 11}\right|$ of $< 3.7\cdot10^{ -6}$ GeV at 90\% confidence level. Moreover, we derive new constraints on $(a_{ \text{ of}}^{ (3)})_{ 00}$ and $(a_{ \text{ of}}^{ (3)})_{ 10}$.
Categories: nucl-ex hep-ex hep-ph