Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Order by disorder and gauge-like degeneracy in quantum pyrochlore
  antiferromagnet   The (three-dimensional) pyrochlore lattice antiferromagnet with Heisenberg
spins of large spin length $S$ is a highly frustrated model with an macroscopic
degeneracy of classical ground states. The zero-point energy of (harmonic
order) spin wave fluctuations distinguishes a subset of these states. I derive
an approximate but illuminating {\it effective Hamiltonian}, acting within the
subspace of Ising spin configurations representing the {\it collinear} ground
states. It consists of products of Ising spins around loops, i.e has the form
of a $Z_2$ lattice gauge theory. The remaining ground state entropy is still
infinite but not extensive, being $O(L)$ for system size $O(L^3)$. All these
ground states have unit cells bigger than those considered previously.

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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: mtrl-th
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The categories of this paper are: econ
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The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph