Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ground state properties of charge and magnetically frustrated
  two--dimensional quantum Josephson--junction arrays   We study a quantum Hamiltonian that models an two--dimensional array of
Josephson junctions with short range Josephson couplings, (given by the
Josephson energy E_J and charging energiey E_C due to the small capacitance of
the junctions. We include the effects from both the self-C0 and the junction-C1
capacitances in the presence of external magnetic flux f=fi/fi0 as well as
uniform background of charges q_{x}. We derive an effective quantum non--linear
sigma-model for the array Hamiltonian which enables us a non mean--field
treatment of the zero--temperature phase transition scenario. We calculate the
ground--state phase diagram, analytically deriving E_J^{crit}(E_C,q_x,f) for
several rational fluxes f=0,1/2,1/3,1/4 and 1/6 that improves upon previous
theoretical treatments based on mean--field approximations.

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The categories of this paper are: bayes-an
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg