Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Sum rule for photon target   The amplitude of zero angle scattering of electron on photon in the 3-rd QED
order of fine structure constant with $\gamma^*\gamma$ intermediate state
converting into quark--antiquark is considered. Utilizing analytic properties
of elastic photon--photon scattering amplitude an explicit expression for
differential cross- section of quark--antiquark pair production at
electron-photon collision in peripheral kinematics is derived apparently.
Limiting case of small transferred momenta with an application of the
Weizs\"acker-Williams like relation gives the sum rule for photon target,
bringing into the relation the sum of ratios of the four power of the quark
charges to squared quark masses with integral over the total $\gamma\gamma \to
2 jets$ cross--section.

18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th