Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Instanton IR stabilization in the nonperturbative confining vacuum   The influence of nonperturbative fields on instantons in quantum
chromodynamics is studied. Nonperturbative vacuum is described in terms of
nonlocal gauge invariant vacuum averages of gluon field strength. Effective
action for instanton is derived in bilocal approximation and it is demonstrated
that stochastic background gluon fields are responsible for infra-red (IR)
stabilization of instantons. Dependence of characteristic instanton size on
gluon condensate and correlation length in nonperturbative vacuum is found. It
is shown that instanton size in QCD is of order of 0.25 fm. Comparison of
obtained instanton size distribution with lattice data is made.

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The categories of this paper are: chem-ph
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The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: supr-con
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The categories of this paper are: q-bio
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an