About lepton polarization in e+e- → μ+μ- process with neutral weak current consideration

Muon polarization in the process e+e- → μ+μ-, caused by Z-boson exchange, is calculated. It is shown that at high energies spirality changes its sign: at ε > 0.85 M, where M - is Z-boson mass, the muon spirality is negative, and at ε < 0.85 M it is positive. The observation of predicted spirality asymmetry at high energies will be a new proof of the justice of electroweak interaction theory