Polarization effects ine+e−→Z0γ

Polarizations of ${Z}^{0}$ and \ensuremath{\gamma} in the reaction ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${Z}^{0}$\ensuremath{\gamma} near the ${Z}^{0}$ peak are obtained through the density matrix of ${Z}^{0}$ and Stokes parameters of \ensuremath{\gamma}, respectively. Their dependence on the linear polarizations of incident electron-positron beams and their influence on the decay of ${Z}^{0}$ into two spin-(1/2 fermions f and f\ifmmode\bar\else\textasciimacron\fi{} are discussed in the standard model. It is shown that the longitudinal polarization of incident electron beam can enhance the circular polarization of the outgoing photon beam.