Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin-orbit pendulum in Dirac oscillator   The dynamics of wavepackets in a relativistic Dirac oscillator (DO) is
considered. A comparison to nonrelativistic spin-orbit pendulum effect is
discussed. Particular relativistic effects, like Zitterbewegung in spin motion,
are found in Dirac representation. This trembling motion disappears in
Foldy-Wouthuysen representation. A substantial difference between the dynamics
of wavepackets corresponding to circular and linear orbits of a particle is
obtained and discussed.

25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph