Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermodynamic Properties and Elementary Excitations in Quantum
  Sine-Gordon Spin System KCuGaF6   Thermodynamic properties and elementary excitations in $S=1/2$
one-dimensional Heisenberg antiferromagnet KCuGaF$_6$ were investigated by
magnetic susceptibility, specific heat and ESR measurements. Due to the
Dzyaloshinsky-Moriya interaction with alternating $D$-vectors and/or the
staggered $g$-tensor, the staggered magnetic field is induced when subjected to
external magnetic field. Specific heat in magnetic field clearly shows the
formation of excitation gap, which is attributed to the staggered magnetic
field. The specific heat data was analyzed on the basis of the quantum
sine-Gordon (SG) model. We observed many ESR modes including one soliton and
three breather excitations characteristic of the quantum SG model.

22
The categories of this paper are: chao-dyn
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ