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 f^μA and f^μV are derived. © 1998 Elsevier Science B.V. All rights reserved.