Some remarks on the search for CP violation in Z -decays

Abstract

We discuss some issues arising in the search for CP violation in the decays Z → τ+ τ− and Z → bbX. The form-factor and the effective Lagrangian approach to parametrize CP-violating effects are compared. We emphasize the interest to study both real and imaginary parts of CP-violating form factors like the weak dipole moment form factor ${d_∢u^Z}={(m_Z^2)}$ of the τ-lepton. We propose an “optimal” way to search for CP violation when Z → bbX events have to be selected on a statistical basis from the total number of Z hadronic decays.