Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum scalar field in quantum gravity: the vacuum in the spherically
  symmetric case   We study gravity coupled to a scalar field in spherical symmetry using loop
quantum gravity techniques. Since this model has local degrees of freedom, one
has to face ``the problem of dynamics'', that is, diffeomorphism and
Hamiltonian constraints that do not form a Lie algebra. We tackle the problem
using the ``uniform discretization'' technique. We study the expectation value
of the master constraint and argue that among the states that minimize the
master constraint is one that incorporates the usual Fock vacuum for the matter
content of the theory.

11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con