Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On first-arrival-time distributions for a Dirac electron in 1+1
  dimensions   For the special case of freely evolving Dirac electrons in $1 + 1$
dimensions, Feynman checkerboard paths have previously been used to derive
Wigner's arrival-time distribution which includes all arrivals. Here, an
attempt is made to use these paths to determine the corresponding distribution
of first-arrival times. Simple analytic expressions are obtained for the
relevant components of the first-arrival propagator. These are used to
investigate the relative importance of the first-arrival contribution to the
Wigner arrival-time distribution and of the contribution arising from
interference between first and later (i.e. second, third, ...) arrivals. It is
found that a distribution of (intrinsic) first-arrival times for a Dirac
electron cannot in general be consistently defined using checkerboard paths,
not even approximately in the nonrelativistic regime.

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The categories of this paper are: plasm-ph
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The categories of this paper are: nlin
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
3
The categories of this paper are: physics
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The categories of this paper are: q-bio
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The categories of this paper are: hep-th
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The categories of this paper are: gr-qc
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The categories of this paper are: astro-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci
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The categories of this paper are: math
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex