Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ground state and low excitations of an integrable chain with alternating
  spins   An anisotropic integrable spin chain, consisting of spins $s=1$ and
$s=\frac{1}{2}$, is investigated \cite{devega}. It is characterized by two real
parameters $\bar{c}$ and $\tilde{c}$, the coupling constants of the spin
interactions. For the case $\bar{c}<0$ and $\tilde{c}<0$ the ground state
configuration is obtained by means of thermodynamic Bethe ansatz. Furthermore
the low excitations are calculated. It turns out, that apart from free magnon
states being the holes in the ground state rapidity distribution, there exist
bound states given by special string solutions of Bethe ansatz equations (BAE)
in analogy to \cite{babelon}. The dispersion law of these excitations is
calculated numerically.

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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
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The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: ao-sci
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The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio