We present measurements of spectral moments extracted from the invariant mass distributions of the final states of hadronic τ decay products recorded in the CLEO detector. From a fit of theoretical predictions to the measurements of spectral moments and the total hadronic decay width of the τ, we determine the strong coupling constant and a set of non-perturbative QCD parameters. The strong coupling constant is measured to be αs(mτ) = 0.306 ± 0.024, which when extrapolated to the Z mass, yields αs(Mz) = 0.114 ± 0.003.
Bibliographical noteFunding Information:
We gratefully acknowledget he effort of the CESR staff in providing us with excellent luminosity and running conditions. JPA., J.R.P., and 1.PJ.S. thank the NY1 program of the NSF, G.E. thanks the Heisenberg Foundation, I.P.J.S. and T.S. thank the TNRLC, K.K.G., M.S., H.N.N., T.S., and H.Y. thank the OJI program of DOE, J.R.P thanks the A.P. Sloan Foundation, and A.W. thanks the Alexander von Humboldt Stiftung for support. This work was supportedb y the National Science Foundation, the U.S. Departmento f Energy and the Natural Sciences and Engineering Re-searchC ouncil of Canada. We especially thank F. Le Diberder of Orsay for very helpful communications and for providing the computerp rogram used to compute the theoreticalp redictions.