Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bekenstein model and the time variation of the strong coupling constant   We propose to generalize Bekenstein model for the time variation of the fine
structure "constant" $\alpha_{em}$ to QCD strong coupling constant $\alpha_S$.
We find that, except for a ``fine tuned'' choice of the free parameters, the
extension can not be performed trivially without being in conflict with
experimental constraints and this rules out $\alpha_S$ variability. This is due
largely to the huge numerical value of the QCD vacuum gluon condensate when
compared to the matter density of the universe.

4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int