Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the grounding of spin effects in theory of synchrotron radiation   The problem of the uniqueness in the introduction of spin operators in the
synchrotron radiation theory is discussed. For this purpose we give the
invariant spin projections on the basis of the spin projections in the rest
frame. The spin equations are used to construct the integrals of motion in the
presence of the external electromagnetic field.

36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn