Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Order alpha^7 ln(1/alpha) Contribution to Positronium Hyperfine
  Splitting   The logarithmically enhanced alpha^7 ln(1/alpha) contribution to the
hyperfine splitting of the positronium ground-state energy levels is calculated
in the framework of dimensionally regularized nonrelativistic quantum
electrodynamics. The correction is negative and amounts to about 1/3 of the
leading logarithmic alpha^7 ln^2(1/alpha) one. The discrepancy between the
experimental measurements and the theoretical prediction is reduced.

24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin