Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gluon Field Strength Correlation Functions within a Constrained
  Instanton Model   We suggest a constrained instanton (CI) solution in the physical QCD vacuum
which is described by large-scale vacuum field fluctuations. This solution
decays exponentially at large distances. It is stable only if the interaction
of the instanton with the background vacuum field is small and additional
constraints are introduced. The CI solution is explicitly constructed in the
ansatz form, and the two-point vacuum correlator of gluon field strengths is
calculated in the framework of the effective instanton vacuum model. At small
distances the results are qualitatively similar to the single instanton (SI)
case, in particular, the form factor $D_{1}$ is small, which is in agreement
with the lattice calculations.

36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci