Optimal observable to measure the imaginary component of the τ anomalous weak-magnetic dipole moment

The feasibility of measuring the imaginary component of the τ anomalous weak-magnetic dipole moment (aτW) is discussed. From a sample of data comparable to that obtained in the period 90–95 by one of the LEP experiments the expected error in the anomalous weak-magnetic dipole moment for the π−π+, π±ϱ∓ and ϱ−ϱ+ final states is estimated to be |Im(aτW)| < 1.9 10−3 at the 95% confidence level.