Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Determination of the gluon condensate from data in the charm-quark
  region   The gluon condensate, $\langle \frac{\alpha_s}{\pi} G^2 \rangle$, i.e. the
leading order power correction in the operator product expansion of current
correlators in QCD at short distances, is determined from $e^+ e^-$
annihilation data in the charm-quark region. This determination is based on
finite energy QCD sum rules, weighted by a suitable integration kernel to (i)
account for potential quark-hadron duality violations, (ii) enhance the
contribution of the well known first two narrow resonances, the $J/\psi$ and
the $\psi(2S)$, while quenching substantially the data region beyond, and (iii)
reinforce the role of the gluon condensate in the sum rules. By using a kernel
exhibiting a singularity at the origin, the gluon condensate enters the Cauchy
residue at the pole through the low energy QCD expansion of the vector current
correlator. These features allow for a reasonably precise determination of the
condensate, i.e. $\langle \frac{\alpha_s}{\pi} G^2 \rangle =0.037 \,\pm\, 0.015
\;{\mbox{GeV}}^4$.

21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex