Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Geometric spin foams, Yang-Mills theory and background-independent
  models   We review the dual transformation from pure lattice gauge theory to spin foam
models with an emphasis on a geometric viewpoint. This allows us to give a
simple dual formulation of SU(N) Yang-Mills theory, where spin foam surfaces
are weighted with the exponentiated area. In the case of gravity, we introduce
a symmetry condition which demands that the amplitude of an individual spin
foam depends only on its geometric properties and not on the lattice on which
it is defined. For models that have this property, we define a new sum over
abstract spin foams that is independent of any choice of lattice or
triangulation. We show that a version of the Barrett-Crane model satisfies our
symmetry requirement.

22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics