Measurement of the axial-vector
determination of from hadronic decays
R. Barate et al.
Laboratoire de Physique des Particules (LAPP), IN2P3-CNRS, F-74019 Annecy-le-Vieux Cedex, France
Received: 26 January 1998 / Published online: 15 June 1998
An analysis based on 124000 selected pairs recorded by the ALEPH detector at LEP provides the vector (V) and axial-vector (A) spectral functions of hadronic decays together with their total widths. This allows the evaluation of finite energy chiral sum rules that are weighted integrals over the (V-A) spectral functions. In addition, a precise measurement of along with a determination of nonperturbative contributions at the mass scale is performed. The experimentally and theoretically most robust determination of is obtained from the (V+A) fit that yields giving after the extrapolation to the mass of the Z boson. The approach of the Operator Product Expansion (OPE) is tested experimentally studying the evolution of the hadronic widths to masses smaller than the mass.