Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Entanglement Entropy and Quantum Field Theory   We carry out a systematic study of entanglement entropy in relativistic
quantum field theory. This is defined as the von Neumann entropy S_A=-Tr rho_A
log rho_A corresponding to the reduced density matrix rho_A of a subsystem A.
For the case of a 1+1-dimensional critical system, whose continuum limit is a
conformal field theory with central charge c, we re-derive the result
S_A\sim(c/3) log(l) of Holzhey et al. when A is a finite interval of length l
in an infinite system, and extend it to many other cases: finite systems,finite
temperatures, and when A consists of an arbitrary number of disjoint intervals.
For such a system away from its critical point, when the correlation length \xi
is large but finite, we show that S_A\sim{\cal A}(c/6)\log\xi, where \cal A is
the number of boundary points of A. These results are verified for a free
massive field theory, which is also used to confirm a scaling ansatz for the
case of finite-size off-critical systems, and for integrable lattice models,
such as the Ising and XXZ models, which are solvable by corner transfer matrix
methods. Finally the free-field results are extended to higher dimensions, and
used to motivate a scaling form for the singular part of the entanglement
entropy near a quantum phase transition.

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The categories of this paper are: hep-ex
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The categories of this paper are: comp-gas
3
The categories of this paper are: physics
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
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The categories of this paper are: cs
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: astro-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat
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The categories of this paper are: math-ph
29
The categories of this paper are: funct-an