Spin Effects in Neutralino Production in $e^+e^-$ Annihilation with   polarized beams
  We study the process e^+ e^- -> chi^0_1 chi^0_2 and the subsequent decay chi^0_2 -> chi^0_1 l^{+} l^{-}$ with polarized beams, including the complete spin correlations of chi^0_2$. We present numerical results for the lepton energy and angular distributions, and for the distribution of the opening angle between the leptons for sqrt{s}=500 GeV. The effects of spin correlations are important in the lepton angular distribution, especially for gaugino-like neutralinos. The opening angle distribution is particularly suitable for distinguishing between higgsino- and gaugino-like neutralinos. The polarized cross sections and lepton angular distributions are very sensitive to the mixing of the neutralinos. 
G. Moortgat-Pick, H. Fraas, A. Bartl, W. Majerotto