Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Finite-temperature correlations in a quantum spin chain near saturation   Inelastic neutron-scattering and finite-temperature density matrix
renormalization group (DMRG) calculations are used to investigate the spin
excitation spectrum of the $S=1/2$ Heisenberg spin chain compound
K$_2$CuSO$_4$Cl$_2$ at several temperatures in a magnetic field near
saturation. Critical correlations characteristic of the predicted $z=2$, $d=1$
quantum phase transition occurring at saturation are shown to be consistent
with the observed neutron spectra. The data is well described with a scaling
function computed using a free fermion description of the spins, valid close to
saturation, and the corresponding scaling limits. One of the most prominent
non-universal spectral features of the data is a novel thermally activated
longitudinal mode that remains underdamped across most of the Brillouin zone.

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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-ex
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
2
The categories of this paper are: math
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The categories of this paper are: acc-phys
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The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: funct-an
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The categories of this paper are: econ
0
The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga