Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The "proton spin crisis" - a quantum query   The "proton spin crisis" was introduced in the late 1980s, when the
EMC-experiment revealed that little or nothing of a proton's spin seemed to be
carried by its quarks. The main objective of this paper is to point out that it
is wrong to assume that the proton spin, measured by completely different
experimental setups, should be the same in all circumstances.

11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an