Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Diffractons: solitary waves created by diffraction in periodic media   A new class of solitary waves arises in the solution of nonlinear wave
equations with constant impedance and no dispersive terms. They depend on a
balance between nonlinearity and a dispersion-like effect due to spatial
variation in the sound speed of the medium. A high-order homogenized model
confirms this effective dispersive behavior and its solutions agree well with
those obtained by direct simulation of the variable-coefficient system. These
waves are observed to be long-time stable, globally attracting solutions that
arise in general as solutions to nonlinear wave problems with
periodically-varying sound speed. They share some properties with known classes
of solitary waves, but possess important differences as well.

30
The categories of this paper are: q-alg
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph