Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the essential spectrum of the Jansen-Hess operator for two-electron
  ions   Based on the HVZ theorem and dilation analyticity of the pseudorelativistic
no-pair Jansen-Hess operator, it is shown that for subcritical potential
strength (Z < 90) the singular continuous spectrum is absent. The bound is
slightly higher (Z < 102) for the Brown-Ravenhall operator whose eigenvalues
are, by the virial theorem, confined to <2m if Z<50.math/m

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The categories of this paper are: cs
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
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The categories of this paper are: hep-ex
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
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The categories of this paper are: eess
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg