Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Implications of the ALEPH tau-Lepton Decay Data for Perturbative and
  Non-Perturbative QCD   We use ALEPH data on hadronic $\tau$ decays in order to calculate Euclidean
coordinate space correlation functions in the vector and axial-vector channels.
The linear combination $V-A$ receives no perturbative contribution and is
quantitatively reproduced by the instanton liquid model. In the case of $V+A$
the instanton calculation is in good agreement with the data once perturbative
corrections are included. These corrections clearly show the evolution of
$\alpha_s$. We also analyze the range of validity of the Operator Product
Expansion (OPE). In the $V-A$ channel we find a dimension $d=6$ contribution
which is comparable to the original SVZ estimate, but the instanton model
provides a different non-singular term of the same magnitude. In the $V+A$ case
both the OPE and the instanton model predict the same $d=4$ power correction
induced by the gluon condensate, but it is masked by much larger perturbative
contributions. We conclude that the range of validity of the OPE is limited to
$x\lsim0.3$ fm, whereas the instanton model describes the data over the entire
range.

34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph