New Limits on Local Lorentz Invariance from Hg and Cs Magnetometers

Abstract

The relative frequency of Hg and Cs mgnetometers is monitored as a function of the orientation of the applied magnetic field with respect to the fixed stars. The observed stability of the relative frequency limits electron and nucleon local Lorentz invariance violating effects to less than 200 \ensuremath{\mu}Hz and 110 nHz, respectively. These results represent an improvement over the best published results by an order of magnitude for electron effects and by a factor of 240 for nuclear effects. The result also sets an upper limit of 200 eV on the Fermi level of a degenerate remnant neutrino background.