Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Shell structure and pairing for interacting fermions in a trap   The shell structures for weakly interacting fermions in harmonic oscillator
traps at zero temperature undergo several transitions depending on the number
of particles in the trap and their interaction strength. Calculations of the
one and two particle spectra give the pairing gaps, and the many particle state
is constructed by the seniority scheme. For sufficiently few particles, $N\la
10^4$, the pairing field exceeds the mean-field splitting of single particle
levels at the Fermi surface and the greater number of almost degenerate states
due to the SU(3) symmetry in the harmonic oscillator shell lead to {\it
supergaps}. Deformation and rotation are also discussed.

14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci