Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Low-lying excitations and thermodynamics of an antiferromagnetic
  Heisenberg fractal system of a dimension between one and two   We investigate a frustrated Heisenberg spin-1/2 antiferromagnet on a fractal
lattice of dimension d=ln3/ln2 (Sierpinski gasket). Calculations were performed
using (a) exact diagonalization of all eigenstates and eigenvectors for systems
up to N=15 and (b) the Decoupled-Cell Quantum-Monte-Carlo method for systems up
to N=366. We present the low-lying spectrum and the specific heat. The specific
heat shows a second maximum in the low-temperature region. This behavior is
similar to the behavior of the quantum Heisenberg antiferromagnet on a kagome
lattice and suggests a disordered ground state and a spin gap in the considered
system.

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The categories of this paper are: gr-qc
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The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
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The categories of this paper are: math
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The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an