Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Derivation of Deser's Formula and Electromagnetic Corrections to the
  Pionium Life Time   We give the modern derivation of Deser's formula using analytic continuation
of the scattering amplitude as a function of momentum. The electromagnetic
corrections to the pionium lifetime are given as evaluated in a potential
model.

17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th