Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Canonical theory of spherically symmetric spacetimes with
  cross-streaming null dusts   The Hamiltonian dynamics of two-component spherically symmetric null dust is
studied with regard to the quantum theory of gravitational collapse. The
components--the ingoing and outgoing dusts--are assumed to interact only
through gravitation. Different kinds of singularities, naked or "clothed", that
can form during collapse processes are described. The general canonical
formulation of the one-component null-dust dynamics by Bicak and Kuchar is
restricted to the spherically symmetric case and used to construct an action
for the two components. The transformation from a metric variable to the
quasilocal mass is shown to simplify the mathematics. The action is reduced by
a choice of gauge and the corresponding true Hamiltonian is written down.
Asymptotic coordinates and energy densities of dust shells are shown to form a
complete set of Dirac observables. The action of the asymptotic time
translation on the observables is defined but it has been calculated explicitly
only in the case of one-component dust (Vaidya metric).

0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga