A Measurement of the Michel Parameters in Leptonic Decays of the Tau

Authors

R. Ammar, University of Kansas - Lawrence
Kenneth A. Bloom, University of Nebraska-LincolnFollow
CLEO Collaboration

Date of this Version

6-23-1997

Comments

Published by American Physical Society. Phys. Rev. Lett. 78, 4686 (1997). Permission to use. http://prl.aps.org. Copyright © 1997 American Physical Society.

Abstract

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 ρ_eμ = 0.735 ± 0.013 ± 0.008 and η_eμ = 20.015 ± 0.061 ± 0.062, where the first error is statistical and the second systematic. We also present measurements for the parameters for e and μ final states separately.