DOI 10.1007/s100529800895
Measurement of the axial-vector
spectral functions
and
determination of
from hadronic
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 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.
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