Measurement of the Weinberg Angle in an Experiment at the Super Charm Tau Factory with a Polarized Beam

Measurement of the effective weak mixing angle $${\theta_{\textrm{eff}}}$$ in an experiment at the Super Charm Tau Factory is discussed for the case of a longitudinal polarization of electrons. A method for measuring the average electron beam polarization by means of analyzing the differential cross section for the decay process $${{J/\psi}}\to[\Lambda\to p\pi^{-}][{\bar{\Lambda}}\to{\bar{p}}\pi^{+}]$$ is proposed. At a collider luminosity of $$10^{35}\textrm{cm}^{-2}\textrm{s}^{-1}$$ and a polarization degree of $$0.8$$ , the parameter $${\sin^{2}{{\theta_{\textrm{eff}}}}}$$ can be measured to a relative precision better than $$1\%$$ , which will be sufficient for observing the deviation of $${\sin^{2}{{\theta_{\textrm{eff}}}}}$$ from its value at the $$Z$$ -boson peak.