2 research outputs found
Vector and Axial-Vector Spectral Functions and QCD
We present new results of the tau hadronic spectral function analysis using
data accumulated by the ALEPH detector at LEP during the years 1991-94. In
addition to the vector spectral functions, the axial-vector spectral functions
and, separately, the tau --> 3pi nu as well as the tau --> pi 2pi0 nu spectral
functions are determined from their respective unfolded, i.e., physical
invariant mass spectra. The spectral functions are applied to QCD chiral sum
rules in order to extract information about saturation at the tau mass scale.
Using the the semi-leptonic tau decay rate for vector and axial-vector currents
in addition to spectral moments, we obtain precise measurements of the strong
coupling constant alpha_s(M_tau) and the contributing non-perturbative power
terms. The evolution to the Z mass yields alpha_s(M_Z) = 0.1219 +/- 0.0019.Comment: 15 pages, 12 figures, LaTex, Talk given at the Fourth International
Workshop on Tau Lepton Physics (TAU96), Colorado, September 199