Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum Theory of Half-integer Spin Free Particles from the Perspective
  of the Majorana Equation   In this study, the Majorana equation for particles with arbitrary spin is
solved for a half-integer spin free particle. The solution for the fundamental
state, corresponding to the reference frame in which the particle is at rest,
is compared with that obtained using the Dirac equation, especially as regards
the approximation in the relativistic limit, in which the speed of the particle
is close to that of light. Furthermore, the solutions that Majorana defines
unphysical, proving that their occupation probability increases with the
particle velocity, are taken into consideration. The anomalous behavior
exhibited by these states also shows that for high-energy particles with small
mass, transitions from a bradyonic state to a tachyonic state become possible.

1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
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The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
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The categories of this paper are: quant-ph
18
The categories of this paper are: econ