Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A note on the principle of least action and Dirac matrices   Many Lagrangians of physical theories can be expressed as eigenvalues of
certain, relatively simple, matrices involving Dirac gamma matrices. We give
concrete examples for Lagrangian corresponding to a point particle coupled to
electromagnetic field, electrodynamics, nonabelian gauge theories, extended
objects and gravity. We also discuss (in case of a point particle) what are the
implications of the least action principle applied to matrix Lagrangians.

3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: funct-an
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The categories of this paper are: eess
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The categories of this paper are: bayes-an
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The categories of this paper are: solv-int
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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga