Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: QCD Sum Rules, a Modern Perspective   An introduction to the method of QCD sum rules is given for those who want to
learn how to use this method. Furthermore, we discuss various applications of
sum rules, from the determination of quark masses to the calculation of
hadronic form factors and structure functions. Finally, we explain the idea of
the light-cone sum rules and outline the recent development of this approach.

8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat
26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga