Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Algorithmic approach to diagrammatic expansions for real-frequency
  evaluation of susceptibility functions   We systematically generate the perturbative expansion for the two-particle
spin susceptibility in the Feynman diagrammatic formalism and apply this
expansion to a model system - the single-band Hubbard model on a square
lattice. We make use of algorithmic Matsubara integration (AMI) [A.
Taheridehkordi, S. H. Curnoe, and J. P. F. LeBlanc, Phys. Rev. B 99, 035120
(2019)] to analytically evaluate Matsubara frequency summations, allowing us to
symbolically impose analytic continuation to the real frequency axis. We
minimize our computational expense by applying graph invariant transformations
[Amir Taheridehkordi, S. H. Curnoe, and J. P. F. LeBlanc, Phys. Rev. B 101,
125109 (2020)]. We highlight extensions of the random-phase approximation and
T-matrix methods that, due to AMI, become tractable. We present results for
weak interaction strength where the direct perturbative expansion is
convergent, and verify our results on the Matsubara axis by comparison to other
numerical methods. By examining the spin susceptibility as a function of
real-frequency via an order-by-order expansion we can identify precisely what
role higher order corrections play on spin susceptibility and demonstrate the
utility and limitations of our approach.

22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ