Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Resummation of Feynman Diagrams and the Inversion of Matrices   In many field theoretical models one has to resum two- and four-legged
subdiagrams in order to determine their behaviour. In this article we present a
novel formalism which does this in a nice way. It is based on the central limit
theorem of probability and an inversion formula for matrices which is obtained
by repeated application of the Feshbach projection method. We discuss
applications to the Anderson model, to the many-electron system and to the
phi^4-model. In particular, for the many-electron system with attractive
delta-interaction, we find that the existence of a BCS gap and a macroscopic
value of the Hubbard-Stratonovich field for zero momentum enforce each other.

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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
1
The categories of this paper are: cs
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio