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 θ_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/ψ→[Λ→ pπ^-][Λ̅→p̅π^+] is proposed. At a collider luminosity of 10^35cm^-2s^-1 and a polarization degree of 0.8 , the parameter sin^2θ_eff can be measured to a relative precision better than 1% , which will be sufficient for observing the deviation of sin^2θ_eff from its value at the Z -boson peak.