Test of CP invariance in Z→μ+μ−γ decay

We report on the first test of CP invariance in Z decays with hard photon radiation. The data recorded with the L3 detector at centre-of-mass energies near the Z resonance are used to search for CP violation in the reaction e+e−→μ+μ−γ. No evidence for CP violation is found and limits on the CP-violating form factors fμA and fμV are derived.