Test of CPT and Lorentz invariance from muonium spectroscopy

TL;DR

This paper tests CPT and Lorentz invariance using muonium microwave spectroscopy, finding no violations and setting new, highly sensitive limits on potential symmetry-breaking parameters.

Contribution

It provides the first high-precision test of CPT and Lorentz invariance in muonium, improving sensitivity by an order of magnitude over previous measurements.

Findings

No sidereal variation detected in transition frequencies

Limits on CPT and Lorentz violating parameters at 2×10^{-23} GeV

Achieved Planck scale sensitivity in muonium spectroscopy

Abstract

Following a suggestion of Kostelecky et al. we have 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 $\delta\nu_{12}$ and $\delta\nu_{34}$ to $\nu_{12}$ and $\nu_{34}$, 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 anti-correlated oscillations in $\nu_{12}$ and $\nu_{34}$ at the earth's sidereal frequency. No time dependence was found in $\nu_{12}$ or $\nu_{34}$ at the level of 20 Hz, limiting the size of some CPT and Lorentz violating parameters at the level of $2\times10^{-23}$ GeV, representing Planck scale sensitivity and an order of magnitude improvement in sensitivity over previous limits for the muon.