Using the ARGUS detector at the e+e− storage ring DORIS II, we have
measured the Michel parameters ρ, ξ, and ξδ for
τ±→l±ννˉ decays in τ-pair events produced at
center of mass energies in the region of the Υ resonances. Using
τ∓→ρ∓ν as spin analyzing tags, we find ρe=0.68±0.04±0.08, ξe=1.12±0.20±0.09, ξδe=0.57±0.14±0.07, ρμ=0.69±0.06±0.08, ξμ=1.25±0.27±0.14 and ξδμ=0.72±0.18±0.10. In addition, we report
the combined ARGUS results on ρ, ξ, and ξδ using this work
und previous measurements.Comment: 10 pages, well formatted postscript can be found at
http://pktw06.phy.tu-dresden.de/iktp/pub/desy97-194.p