Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Variational cluster approach for strongly correlated lattice bosons in
  the superfluid phase   We extend the variational cluster approach to deal with strongly correlated
lattice bosons in the superfluid phase. To this end, we reformulate the
approach within a pseudoparticle formalism, whereby cluster excitations are
described by particlelike excitations. The approximation amounts to solving a
multicomponent noninteracting bosonic system by means of a multimode Bogoliubov
approximation. A source-and-drain term is introduced in order to break U(1)
symmetry at the cluster level. We provide an expression for the grand
potential, the single-particle normal and anomalous Green's functions, the
condensate density, and other static quantities. As a first nontrivial
application of the method we choose the two-dimensional Bose-Hubbard model and
evaluate results in both the Mott and the superfluid phases. Our results show
an excellent agreement with quantum Monte Carlo calculations.

36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio