Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Correlations in quantum systems and branch points in the complex plane   Branch points in the complex plane are responsible for avoided level
crossings in closed and open quantum systems. They create not only an exchange
of the wave functions but also a mixing of the states of a quantum system at
high level density. The influence of branch points in the complex plane on the
low-lying states of the system is small.

19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci