Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the existence of internal modes of sine-Gordon kinks   We study whether or not sine-Gordon kinks exhibit internal modes or
``quasimodes.'' By considering the response of the kinks to ac forces and
initial distortions, we show that neither intrinsic internal modes nor
``quasimodes'' exist in contrast to previous reports. However, we do identify a
different kind of internal mode bifurcating from the bottom edge of the phonon
band which arises from the discretization of the system in the numerical
simulations, thus confirming recent predictions.

33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
3
The categories of this paper are: physics
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci