Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Taming singularities of the diagrammatic many-body perturbation theory   In a typical scenario the diagrammatic many-body perturbation theory
generates asymptotic series. Despite non-convergence, the asymptotic expansions
are useful when truncated to a finite number of terms. This is the reason for
popularity of leading-order methods such as $GW$ approximation in condensed
matter, molecular and atomic physics. Emerging higher-order implementations
suffer from the appearance of nonsimple poles in the frequency-dependent
Green's functions and negative spectral densities making self-consistent
determination of the electronic structure impossible. Here a method based on
the Pad\'e approximation for overcomming these difficulties is proposed and
applied to the Hamiltonian describing a core electron coupled to a single
plasmonic excitation. By solving the model purely diagrammatically, expressing
the self-energy in terms of combinatorics of chord diagrams, and regularizing
the diverging perturbative expansions using the Pad\'e approximation the
spectral function is determined self-consistently using 3111 diagrams up to the
sixth order.

23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph