Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Time Dependence of QCD   From astrophysics there are indications that the finestructure constant
$\alpha $ has changed during the past 10 billion years. Within grand
unification one can deduce that also the QCD scale has changed. Tests for a
time variation of this scale are described. The result of the new experiment in
Munich is discussed.

18
The categories of this paper are: econ
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
28
The categories of this paper are: alg-geom