Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The $O(\alpha^2)$ Initial State QED Corrections to $e^+e^- \rightarrow
  \gamma^*/Z_0^*$   We calculate the complete $O(\alpha^2)$ initial state radiation corrections
to $e^+ e^-$ annihilation into a neutral vector boson in a direct analytic
computation without any approximation. The corrections are represented in terms
of iterated incomplete (elliptic) integrals over alphabets of square--root
valued letters. Performing the limit $s \gg m_e^2$, we find discrepancies with
the earlier results of Ref.~\cite{Berends:1987ab} and confirm results obtained
in Ref.~\cite{Blumlein:2011mi} where the effective method of massive operator
matrix elements has been used, which works for all but the power corrections in
$m^2_e/s$. In this way, we also confirm the validity of the factorization of
massive partons in the Drell--Yan process. We add non--logarithmic terms at
$O(\alpha^2)$ which have not been considered in previous calculations. The
final results in the limit $s \gg m_e^2$ can be given in terms of Nielsen
integrals.

23
The categories of this paper are: solv-int
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom