Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron pair forming in an integrable model   We consider a lattice model in which phonons scatter with pairs of electrons.
All eigenvalues and eigenvectors can be obtained analytically. For a suitable
choice of parameters the ground state consists of a Fermi sea of
non-interacting electrons, with on top a layer of paired electrons. The binding
energy of the electron pairs is partly cancelled by an increased kinetic
energy. This results in a gap in the kinetic energy spectrum of the electrons.

32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat