Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rigid particle revisited: extrinsic curvature yields the Dirac equation   We reexamine the model of relativistic particle with higher-derivative term
linear on the first extrinsic curvature (rigidity). The passage from classical
to quantum theory requires a number of rather unexpected steps which we report
here. We found that, contrary to common opinion, quantization of the model in
terms of $so(3.2)$-algebra yields massive Dirac equation.

24
The categories of this paper are: dg-ga
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The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
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The categories of this paper are: eess
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat