Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Three-Loop Corrections to Lamb Shift in Positronium: Electron Factor and
  Polarization   Hard spin-independent three-loop radiative contributions to energy levels in
positronium generated by one-loop radiative insertions in the fermion lines and
exchanged photons are calculated. This is a next step in calculations of all
corrections of order $m\alpha^7$ inspired by the new generation of precise
$1S-2S$ and $2S-2P$ measurements in positronium.

29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin