Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Instantons and Glueballs   We investigate the impact of instantons on scalar glueball properties in a
largely model-independent analytical approach based on the instanton-improved
operator product expansion (IOPE) of the $0^{++}$ glueball correlator. The
instanton contributions turn out to be dominant, to substantially improve the
consistency of the correponding QCD sum rules, and to increase the glueball
residue about fivefold.

25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs