First Measurement of Leptonic Coupling Asymmetries with Polarized Z bosons

Abstract

We present direct measurements of the $Z^0$-lepton coupling asymmetry parameters, $A_e$, $A_{\hat{I}}¼$, and $A_{\ddot{I}}„$, based on a data sample of 12,063 leptonic $Z^0$ decays collected by the SLD detector. The $Z$ bosons are produced in collisions of beams of polarized $e^{-}$ with unpolarized $e^{+}$ at the SLAC Linear Collider. The couplings are extracted from the measurement of the left-right and forward-backward asymmetries for each lepton species. The results are: $A_e=0.152\pm 0.012(stat)\pm 0.001(syst)$, $A_{\hat{I}}¼=0.102\pm 0.034\pm 0.002$, and $A_{\ddot{I}}„=0.195\pm 0.034\pm 0.003$.

10 pages, 1 figure