Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Perturbative Tamm-Dancoff Renormalization   A new two-step renormalization procedure is proposed. In the first step, the
effects of high-energy states are considered in the conventional (Feynman)
perturbation theory. In the second step, the coupling to many-body states is
eliminated by a similarity transformation. The resultant effective Hamiltonian
contains only interactions which do not change particle number. It is subject
to numerical diagonalization. We apply the general procedure to a simple
example for the purpose of illustration.

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The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
1
The categories of this paper are: cs
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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: patt-sol
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The categories of this paper are: hep-ex
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The categories of this paper are: q-fin
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The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
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The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
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The categories of this paper are: funct-an