Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Entanglement in a first order quantum phase transition   The phase diagram of spins 1/2 embedded in a magnetic field mutually
interacting antiferromagnetically is determined. Contrary to the ferromagnetic
case where a second order quantum phase transition occurs, a first order
transition is obtained at zero field. The spectrum is computed for a large
number of spins and allows one to study the ground state entanglement
properties which displays a jump of its concurrence at the critical point.

33
The categories of this paper are: plasm-ph
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The categories of this paper are: eess
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph