Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neural network parametrization of spectral functions from hadronic tau
  decays and determination of QCD vacuum condensates   The spectral function $\rho_{V-A}(s)$ is determined from ALEPH and OPAL data
on hadronic tau decays using a neural network parametrization trained to retain
the full experimental information on errors, their correlations and chiral sum
rules: the DMO sum rule, the first and second Weinberg sum rules and the
electromagnetic mass splitting of the pion sum rule. Nonperturbative QCD vacuum
condensates can then be determined from finite energy sum rules. Our method
minimizes all sources of theoretical uncertainty and bias producing an estimate
of the condensates which is independent of the specific finite energy sum rule
used. The results for the central values of the condensates $O_6$ and $O_8$ are
both negative.

12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex