Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Edge Magnetic Field in the xxz Spin-1/2 Chain   The critical behavior associated with a transverse magnetic field applied at
the edge of a semi-infinite xxz S=1/2 chain is calculated using field theory
techniques. Contrary to a recent claim, we find that the long-time behavior is
given by a renormalization group fixed point corresponding to an infinite field
which polarizes the spin at the edge. The zero temperature entropy and
position-dependent magnetization are calculated.

2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
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The categories of this paper are: physics
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The categories of this paper are: gr-qc
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom