Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraining Variations in the Fine-Structure Constant with the Cosmic
  Microwave Background   Any time variation in the fine-structure constant alters the ionization
history of the universe and therefore changes the pattern of cosmic microwave
background fluctuations. We calculate the changes in the spectrum of these
fluctuations as a function of the change in the fine-structure constant, and we
find that these changes are dominated by the change in the redshift of
recombination due to the shift in the binding energy of hydrogen. We estimate
the accuracy with which the next generation of cosmic microwave background
experiments might constrain any variation in the fine-structure constant at z
of roughly 1000. We find that such experiments could potentially be sensitive
to $|\Delta \alpha/\alpha| \sim 10^{-2} - 10^{-3}$.

11
The categories of this paper are: hep-lat
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
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg