There are two primary experiments that give constraints on the muon sector. First, spin transitions in muonium () have been used to place a bound on for the muon (see Equation (52) for the definition of ) . Even though muonium is a muon-electron system, the muon sector of the mSME can be isolated by placing the muonium in a strong magnetic field and looking for a particular frequency resonance that corresponds to muon spin flips. The sidereal variation of this transition frequency is then tracked yielding a limit on of
The second muon experiment that yields strong limits is the g-2 experiment [58, 39, 72]. In this experiment relativistic (or ) are injected into a storage ring and allowed to decay. The deposit rate of the decay products along the detector is sensitive to the evolution of the spin of the muon, which in turn is a function of for the muon. Lorentz violation changes this evolution equation, and therefore this type of experiments can bound the mSME. As in the case of the experiments in Section 5.1, two types of bounds can be placed from the muon experiment. The first is a direct comparison between the factors for and , which limits the CPT violating coefficient . Furthermore, an analysis of sidereal variations involving only one of the at the current sensitivity in  could bound the coefficient at the level of .
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