Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: One-dimensional Fermi gas with a single impurity in a harmonic trap:
  Perturbative description of the upper branch   The transition from "few to many" has recently been probed experimentally in
an ultra cold harmonically confined one-dimensional lithium gas, in which a
single impurity atom interacts with a background gas consisting of one, two, or
more identical fermions [A. N. Wenz {\em{et al.}}, Science {\bf{342}}, 457
(2013)]. For repulsive interactions between the background or majority atoms
and the impurity, the interaction energy for relatively moderate system sizes
was analyzed and found to converge toward the corresponding expression for an
infinitely large Fermi gas. Motivated by these experimental results, we apply
perturbative techniques to determine the interaction energy for weak and strong
coupling strengths and derive approximate descriptions for the interaction
energy for repulsive interactions with varying strength between the impurity
and the majority atoms and any number of majority atoms.

11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph