Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Freezing of the QCD coupling constant and solutions of Schwinger-Dyson
  equations   We compare phenomenological values of the frozen QCD running coupling
constant ($\alpha_s$) with two classes of solutions obtained through
nonperturbative Schwinger-Dyson equations. We use these same solutions with
frozen coupling constants as well as their respective nonperturbative gluon
propagators to compute the QCD prediction for the asymptotic pion form factor.
Agreement between theory and experiment on $\alpha_s(0)$ and $F_\pi (Q^2)$ is
found only for one of the solutions Schwinger-Dyson equations.

29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg