Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: $2\gamma$ and $3\gamma$ annihilation as calibration processes for high
  energy $e^+ e^-$ colliders   Born differential cross sections and the lowest-order radiative correction to
them are obtained in the kinematics of large-angle final photons emission in
high-energy electron-positron annihilation processes. Taking into account
possible emission of real soft and hard photons in collinear kinematics we show
the validity of the Drell-Yan form of differential cross section with the
nonsinglet structure functions of initial leptons. The leading and next-to
leading contribution to the cross sections is obtained. The relevant numerical
estimations are presented.

20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an