Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Diagrammatic study of optical excitations in correlated systems   The optical conductivity contains relevant information on the properties of
correlated electron systems. In infinite dimensions, where dynamical mean field
theory becomes exact, vertex corrections can be neglected and the conductivity
computed from particle-hole bubbles. An interesting question concerns the
nature and effect of the most relevant vertex corrections in finite-dimensional
systems. A recent numerical study showed that the dominant vertex correction
near an ordering instability with wave vector {\pi} comes from a vertical
ladder, analogous to the Maki-Thompson diagram. Since the RPA version of this
ladder diagram, dubbed {\pi}-ton, can be easily evaluated, this suggests a
simple procedure for incorporating antiferromagnetic or charge density wave
fluctuations into dynamical mean field estimates of the optical conductivity
and related susceptibilities. We implement this procedure for the half-filled
Hubbard model, considering the {\pi}-ton and a double-ladder extension of the
{\pi}-ton, and reveal the spectral signatures of these vertex corrections.

11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
23
The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: q-fin
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The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex