Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: OPE coefficient functions in terms of composite operators only. Singlet
  case   A method for calculating coefficient functions of the operator product
expansion, which was previously derived for the non-singlet case, is
generalized for the singlet coefficient functions. The resulting formula
defines coefficient functions entirely in terms of corresponding singlet
composite operators without applying to elementary (quark and gluon) fields.
Both "diagonal" and "non-diagonal" gluon coefficient functions in the product
expansion of two electromagnetic currents are calculated in QCD. Their
renormalization properties are studied.

36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci