Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Variational principle and free falling in a space-time with torsion   A comparison between the two possible variational principles for the study of
a free falling spinless particle in a space-time with torsion is noted. It is
well known that the autoparallel trajectories can be obtained from a
variational principle based on a non-holonomic mapping, starting with the
standard world-line action. In a contrast, we explore a world-line action with
a modified metric, thinking about the old idea of contorsion (torsion)
potentials. A fixed-ends variational principle can reproduce autoparallel
trajectories without restrictions on space-time torsion. As an illustration we
have considered a perturbative Weitzenb$\ddot{o}$ck space-time. The
non-perturbative problem is stablished at the end.

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The categories of this paper are: math
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex