Neutral-current effects ine+e−→τ+

Abstract

We suggest that the reaction e +e -+T+T-on a +-like resonance may provide a method for testing theories of the weak neutral current. The method is based on the observation that the T decay products from this reaction will have a forward-backward asymmetry induced by the polarization sensitivity of the T decays. We point out that, to the extent that the +-like resonance stands above background, this reaction provides not only an improved counting rate but also relief from the radiative asymmetries that trouble proposals to measure neutral-current asymmetries in e +e -3

P-odd observables at the $\Upsilon$ peak

“…Before entering a complete analysis of the τ observables, to estimate the sensitivity of this process to the vector coupling, let us first consider the τ − longitudinal polarization, suggested in Ref. [5] in another context. We will make a reasonable approximation in order to get a simple and clean result: the resonant diagrams will dominate the process on the Υ(1S) peak.…”

“…T λ,ξ (γZ A ) is the P-violating piece of diagram (3) plus the V A piece of diagram (5) and T λ,ξ (Zγ A ) the corresponding P-violating piece of diagram (4) plus the AV piece of diagram (5). Finally T λ,ξ (Z A,A ) is the contribution of diagram (5) with axial couplings in the initial and final vertices.…”