CPTand Lorentz Tests with Muons

Precision experiments with muons are sensitive to Planck-scale $\mathrm{CPT}$ and Lorentz violation that is undetectable in other tests. Existing data on the muonium ground-state hyperfine structure and on the muon anomalous magnetic moment could be analyzed to provide dimensionless figures of merit for $\mathrm{CPT}$ and Lorentz violation at the levels of $4\times {10}^{-21\mathrm{}}$ and ${10}^{-23\mathrm{}}$.