Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Landau Singularity and the Instability of Vacuum State in QED   In this paper, we argue that the Landau singularity of the coupling constant
in QED reflects the instability of vacuum state, in other words the
perturbative ground state in QED.We do not have a rigorous mathematical proof.
We rather provide strong arguments derived from the theory of stability of
matter developed by Lieb et al on the hand and the theory of weakly interacting
fermion systems developed by Feldman et al on the other hand.

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The categories of this paper are: chem-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-alg
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The categories of this paper are: econ
0
The categories of this paper are: hep-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: stat
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The categories of this paper are: nucl-ex