Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Free Particle on a Circle with Point Interaction   The quantum dynamics of a free particle on a circle with point interaction is
described by a U(2) family of self-adjoint Hamiltonians. We provide a
classification of the family by introducing a number of subfamilies and thereby
analyze the spectral structure in detail. We find that the spectrum depends on
a subset of U(2) parameters rather than the entire U(2) needed for the
Hamiltonians, and that in particular there exists a subfamily in U(2) where the
spectrum becomes parameter-independent. We also show that, in some specific
cases, the WKB semiclassical approximation becomes exact (modulo phases) for
the system.

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The categories of this paper are: physics
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The categories of this paper are: cond-mat
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: adap-org
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The categories of this paper are: supr-con
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The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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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: cs
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The categories of this paper are: comp-gas