Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Theory of Nuclear Magnetic Relaxation in Haldane Gap Materials: An
  Illustration of the Use of (1+1)-Dimensional Field Theory Techniques
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg