Experimental study of electroweak parameters at PETRA energies (12< or =E/sub c. m. /< or =36. 7 GeV)

We have performed a high-statistics measurement of Bhabha scattering and of the production of hadrons in electron-positron annihilation at PETRA energies (12< or =..sqrt..s-bar< or =36.7 GeV). Combining the results with measurements of ..mu../sup +/..mu../sup -/ and tau/sup +/tau/sup -/ production enables us to compare our results with electroweak theory. We find sin/sup 2/theta/sub W/ = 0.27 +- 0.08. This is in good agreement with the value obtained from neutrino experiments which were carried out in entirely different kinematic regions.