τ-e and τ-μ universality from τ→πν decays

It is pointed out that a comparison of measurements of τ→πν decays with π→μν and π→eν decays can be used to obtain accurate measures of τ-μ and τ-e universality. From current data on these processes it is found that the ratios of the electroweak charged-current couplings of the τ to those of the muon and electron are ${\mathit{g}}_{\mathrm{\tau }}$/${\mathit{g}}_{\mathrm{\mu }}$=0.983±0.025 and ${\mathit{g}}_{\mathrm{\tau }}$/${\mathit{g}}_{\mathit{e}}$=0.986±0.026, in agreement with the hypothesis of universality.