Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum unitary evolution of linearly polarized S^1\times S^2 and S^3
  Gowdy models coupled to massless scalar fields   The purpose of this paper is to study in detail the problem of defining
unitary evolution for linearly polarized S^1 x S^2 and S^3 Gowdy models (in
vacuum or coupled to massless scalar fields). We show that in the Fock
quantizations of these systems no choice of acceptable complex structure leads
to a unitary evolution for the original variables. Nonetheless, unitarity can
be recovered by suitable redefinitions of the basic fields. These are dictated
by the time dependent conformal factors that appear in the description of the
standard deparameterized form of these models as field theories in certain
curved backgrounds. We also show the unitary equivalence of the Fock
quantizations obtained from the SO(3)-symmetric complex structures for which
the dynamics is unitarily implemented.

36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas