Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Berry phase: a topological test for the spectrum structure of
  frustrated quantum spin systems   The nature of the low energy spectrum of frustrated quantum spin systems is
investigated by means of a topological test introduced by Y. Hatsugai which
enables to infer the possible existence or absence of a gap between the ground
state and excited states of these systems. The test relies on the determination
of an order parameter which is a Berry phase. The structure of the spectra of
even and odd-legged systems in 2d and 3d is analyzed. Results are confronted
with previous work.

20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph