Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Frustrated Heisenberg antiferromagnet on a pyrochlore lattice   We investigate quantum phase transitions for the $s=1/2$ antiferromagnetic
Heisenberg model on a pyrochlore lattice. By means of a series expansion
starting from isolated tetrahedra, the ground-state phase diagram is
determined. When the ratio of the two competing exchange couplings is varied,
the first-order (second-order) quantum phase transition occurs between the two
spin gap phases (the spin-gap and the antiferromagnetic phases). We also
discuss some properties expected for the s=1 pyrochlore spin system.

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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
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The categories of this paper are: nucl-ex