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

Abstract 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 f μ A and f μ V are derived.