Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ${\cal O}(\alpha\alpha_s)$ corrections to the $\gamma t\bar{t}$ vertex
  at the top quark threshold   We compute the last missing piece of the two-loop ${\cal O}(\alpha \alpha_s)$
corrections to $\gamma t \bar{t}$ vertex at the $t \bar{t}$ threshold due to
the exchange of a $W$ boson and a gluon. This contribution constitutes a
building block of the top quark threshold production cross section at electron
positron colliders.

2
The categories of this paper are: math
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs