Determination of the Michel Parameters rho, xi, and delta in tau-Lepton Decays with tau --> rho nu Tags

Abstract

Using the ARGUS detector at the $e^{+}{e}^{-}$ storage ring DORIS II, we have measured the Michel parameters $\rho$, $\xi$, and $\xi \delta$ for ${\tau }^{\pm }\to l^{\pm }\nu \bar{\nu }$ decays in $\tau$-pair events produced at center of mass energies in the region of the ${\rm Y}$ resonances. Using ${\tau }^{\mp }\to {\rho }^{\mp }\nu$ as spin analyzing tags, we find ${\rho }_e=0.68\pm 0.04\pm 0.08$, ${\xi }_e=1.12\pm 0.20\pm 0.09$, $\xi {\delta }_e=0.57\pm 0.14\pm 0.07$, ${\rho }_{\mu }=0.69\pm 0.06\pm 0.08$, ${\xi }_{\mu }=1.25\pm 0.27\pm 0.14$ and $\xi {\delta }_{\mu }=0.72\pm 0.18\pm 0.10$. In addition, we report the combined ARGUS results on $\rho$, $\xi$, and $\xi \delta$ using this work und previous measurements.

10 pages, well formatted postscript can be found at http://pktw06.phy.tu-dresden.de/iktp/pub/desy97-194.ps

References in corpus (1)

• Measurement of the Tau Neutrino Helicity and the Michel Parameters in Polarized e+e- Collisions

Cited by in corpus (1)

• A Search for the Electric Dipole Moment of the Tau-Lepton