Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Theory of two-particle excitations and the magnetic susceptibility in
  high-Tc cuprate superconductors   Two-particle (2-p) excitations such as spin and charge excitations play a key
role in high-Tc cuprate superconductors (HTSC). On the basis of a
parameter-free theory, which extends the Variational Cluster Approach (a
recently developed embedded cluster method) to 2-p excitations, the magnetic
excitations of HTSC are shown to be reproduced for a Hubbard model within the
relevant strong-coupling regime. In particular, the resonance mode in the
underdoped regime, its intensity and "hour-glass" dispersion are in good
overall agreement with experiments.

6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
36
The categories of this paper are: cmp-lg
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an