We have measured the spectral shape Michel parameters ρ and η using leptonic decays of the τ, recorded by the CLEO II detector. Assuming e - μ universality in the vectorlike couplings, we find ρeμ = 0.735 ± 0.013 ± 0.008, where the first error is statistical and the second systematic. We also present measurements for the parameters for e and μ final states separately.
|Original language||English (US)|
|Number of pages||5|
|Journal||Physical review letters|
|State||Published - Jun 23 1997|