Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Phenomenological analysis of two-photon exchange effects in proton form
  factor measurements   We perform a model-independent phenomenological analysis of experimental data
on proton form factors ratio. We find that only one of the two photon exchange
amplitudes, which we call $\delta G_M$, is responsible for the discrepancy
between Rosenbluth and polarization methods. The linearity of Rosenbluth plots
implies that $\delta G_M$ is approximately linear function of $\epsilon$. The
slope of $\delta G_M$ is extracted from experimental data and is shown to be
consistent with theoretical calculations.

28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat