Measurement of the strong coupling constant and the vector and axial-vector spectral functions in hadronic tau decays
The OPAL Collaboration
K. Ackerstaff8 - et al.
8CERN, European Organisation for Particle Physics, CH-1211 Geneva 23, Switzerland
Received: 23 June 1998 / Published online: 19 February 1999
The spectral functions of the vector current and the axial-vector current have been measured in hadronic decays using the OPAL detector at LEP. Within the framework of the Operator Product Expansion a simultaneous determination of the strong coupling constant , the non-perturbative operators of dimension 6 and 8 and of the gluon condensate has been performed. Different perturbative descriptions have been compared to the data. The Contour Improved Fixed Order Perturbation Theory gives at the -mass scale and at the Z0-mass scale. The values obtained for using Fixed Order Perturbation Theory or Renormalon Chain Resummation are and smaller, respectively. The running of the strong coupling between and has been tested from direct fits to the integrated differential hadronic decay rate .A test of the saturation of QCD sum rules at the -mass scale has been performed.