Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cooperative effect of phonons and electronic correlations for
  superconductivity in cobaltates   We propose that unconventional superconductivity in hydrated sodium cobaltate
$Na_xCoO_2$ results from an interplay of electronic correlations and
electron-phonon interactions. On the basis of the $t-V$ model plus phonons we
found evidences for a) unconventional superconductivity, b) realistic values of
$T_c$ and c) the dome shape existing near $x \sim 0.35$. This picture is
obtained for $V$ close to the critical Coulomb repulsion $V_c$ which separates
the uniform Fermi liquid from $\sqrt{3} \times \sqrt{3}$ CDW ordered phase.

12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex