Test of CPT and Lorentz Invariance from Muonium Spectroscopy

Following a suggestion from Kostelecký et al., we evaluated a test of CPT and Lorentz invariance from the microwave spectroscopy of muonium. Hamiltonian terms beyond the standard model violating CPT and Lorentz invariance would contribute frequency shifts δν₁₂ and δν₃₄ to ν₁₂ and ν₃₄, the two transitions involving muon spin flip, which were precisely measured in ground state muonium in a strong magnetic field of 1.7 T. The shifts would be indicated by anticorrelated oscillations in ν₁₂ and ν₃₄ at the Earth’s sidereal frequency. No time dependence was found in ν₁₂ or ν₃₄ at the level of 20 Hz, limiting the size of some CPT and Lorentz-violating parameters at the level of 2×10^-23GeV.