Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relativistic Three-Fermion Wave Equations in Reformulated QED and
  Relativistic Effects in Muonium Minus   The variational method, within the Hamiltonian formalism of reformulated QED
is used to determine relativistic wave equations for a system of three fermions
of arbitrary mass interacting electromagnetically. The interaction kernels of
the equations are, in essence, the invariant $\mathcal{M}$ matrices in lowest
order. The equations are used to obtain relativistic $O(\alpha^2)$ corrections
to the non-relativistic ground state energy levels of the Muonium negative ion
($\mu^+ e^- e^-$) as well as of $\mathrm{Ps}^-$ and $\mathrm{H}^-$, using
approximate variational three-body wave functions. The results are compared
with other calculations, where available. The relativistic correction for
Mu$^-$ is found to be $-1.0773 \times 10^{-4}$ eV.

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The categories of this paper are: bayes-an
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The categories of this paper are: cs
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The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
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The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
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The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
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The categories of this paper are: eess
8
The categories of this paper are: hep-ex
6
The categories of this paper are: astro-ph
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The categories of this paper are: q-bio
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The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: solv-int