Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Self-Consistent Second Order Perturbation Theory for the Hubbard Model
  in Two Dimensions   We apply self-consistent second order perturbation theory (SCSOPT) with
respect to the on-site repulsive interaction U to study the Hubbard model in
two dimensions. We investigate single particle properties of the model over the
entire doping range at zero temperature. It is shown that as doping decreases
toward half-filling $\omega$-mass enhancement factor increases, while k-mass
enhancement factor decreases. The increase in $\omega$-mass enhancement factor
is larger than the decrease in k-mass enhancement factor, so that total-mass is
larger than that in the non-interacting case. When particle number density per
unit cell n is given by 0.64<n<1.0 interaction enhances anisotropy of the Fermi
surface, whereas at lower densities n<0.64 interaction suppresses anisotropy of
it. Due to the decrease in k-mass enhancement factor the density of states
(DOS) at the Fermi level is suppressed. It is possible to understand the
results within the framework of the weak coupling Fermi liquid theory.

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The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics