Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modulational instability of periodic standing waves in the derivative
  NLS equation   We consider the periodic standing waves in the derivative nonlinear
Schrodinger (DNLS) equation arising in plasma physics. By using a newly
developed algebraic method with two eigenvalues, we classify all periodic
standing waves in terms of eight eigenvalues of the Kaup-Newell spectral
problem located at the end points of the spectral bands outside the real line.
The analytical work is complemented with the numerical approximation of the
spectral bands, this enables us to fully characterize the modulational
instability of the periodic standing waves in the DNLS equation.

1
The categories of this paper are: cs
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org