Springer LINK: The European Physical Journal C - Abstract Volume 4 Issue 3 (1998) pp 409-431

The European Physical Journal C

ISSN: 1434-6044 (printed version)
ISSN: 1434-6052 (electronic version)

Table of Contents

Abstract Volume 4 Issue 3 (1998) pp 409-431
DOI 10.1007/s100529800895

experimental physics:
Measurement of the axial-vector $\tau$ spectral functions and determination of $\alpha_s(M_\tau^2)$ from hadronic $\tau$ decays

ALEPH Collaboration , 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

Abstract. An analysis based on 124 000 selected $\tau$ pairs recorded by the ALEPH detector at LEP provides the vector $(V)$ and axial-vector $(A)$ spectral functions of hadronic $\tau$ 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 $\alpha_s$ along with a determination of nonperturbative contributions at the $\tau$ mass scale is performed. The experimentally and theoretically most robust determination of $\alpha_s(M_\tau^2)$ is obtained from the $(V+A)$ fit that yields $\alpha_s(M_\tau^2)=0.334\pm 0.022$ giving $\alpha_s(M_{\rm Z}^2)=0.1202\pm 0.0027$ 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 $\tau$ hadronic widths to masses smaller than the $\tau$ mass.

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The European Physical Journal C

experimental physics: Measurement of the axial-vector $\tau$ spectral functions and determination of $\alpha_s(M_\tau^2)$ from hadronic $\tau$ decays

experimental physics:
Measurement of the axial-vector $\tau$ spectral functions and determination of $\alpha_s(M_\tau^2)$ from hadronic $\tau$ decays