Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: One-dimensional scattering of fermions on $\delta$-impurities   We study the spectrum of the 1D Dirac Hamiltonian encompassing the bound and
scattering states of a fermion distorted by a static background built from
$\delta$-function potentials. We distinguish between "mass-spike" and
"electrostatic" $\delta$-potentials. Differences in the spectra arising
depending on the type of $\delta$-potential studied are thoroughly explored.

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The categories of this paper are: hep-ex
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
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The categories of this paper are: cs
34
The categories of this paper are: chem-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: physics
16
The categories of this paper are: stat
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The categories of this paper are: nucl-ex