Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pairing in the Hubbard model: the Cu_{5}O_{4} Cluster versus the Cu-O
  plane   We study the Cu_{5}O_{4} cluster by exact diagonalization of a three-band
Hubbard model and show that bound electron or hole pairs are obtained at
appropriate fillings, and produce superconducting flux quantisation.
  The results extend earlier cluster studies and illustrate a canonical
transformation approach to pairing that we have developed recently for the full
plane. The quasiparticles that in the many-body problem behave like Cooper
pairs are W=0 pairs, that is, two-hole eigenstates of the Hubbard Hamiltonian
with vanishing on-site repulsion. The cluster allows W=0 pairs of d symmetry,
due to a spin fluctuation, and s symmetry, due to a charge fluctuation. Flux
quantisation is shown to be a manifestation of symmetry properties that hold
for clusters of arbitrary size.

21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph