Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Varying Constants   We review some string-inspired theoretical models which incorporate a
correlated spacetime variation of coupling constants while remaining naturally
compatible both with phenomenological constraints coming from geochemical data
(Oklo; Rhenium decay) and with present equivalence principle tests. Barring
unnatural fine-tunings of parameters, a variation of the fine-structure
constant as large as that recently ``observed'' by Webb et al. in quasar
absorption spectra appears to be incompatible with these phenomenological
constraints. Independently of any model, it is emphasized that the best
experimental probe of varying constants are high-precision tests of the
universality of free fall, such as MICROSCOPE and STEP. Recent claims by
Bekenstein that fine-structure-constant variability does not imply detectable
violations of the equivalence principle are shown to be untenable.

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The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
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The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
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The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
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The categories of this paper are: comp-gas