Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hamiltonian spacetime dynamics with a spherical null-dust shell   We consider the Hamiltonian dynamics of spherically symmetric Einstein
gravity with a thin null-dust shell, under boundary conditions that fix the
evolution of the spatial hypersurfaces at the two asymptotically flat
infinities of a Kruskal-like manifold. The constraints are eliminated via a
Kuchar-type canonical transformation and Hamiltonian reduction. The reduced
phase space $\tilde\Gamma$ consists of two disconnected copies of $R^4$, each
associated with one direction of the shell motion. The right-moving and
left-moving test shell limits can be attached to the respective components of
$\tilde\Gamma$ as smooth boundaries with topology $R^3$. Choosing the
right-hand-side and left-hand-side masses as configuration variables provides a
global canonical chart on each component of $\tilde\Gamma$, and renders the
Hamiltonian simple, but encodes the shell dynamics in the momenta in a
convoluted way. Choosing the shell curvature radius and the "interior" mass as
configuration variables renders the shell dynamics transparent in an
arbitrarily specifiable stationary gauge "exterior" to the shell, but the
resulting local canonical charts do not cover the three-dimensional subset of
$\tilde\Gamma$ that corresponds to a horizon-straddling shell. When the
evolution at the infinities is freed by introducing parametrization clocks, we
find on the unreduced phase space a global canonical chart that completely
decouples the physical degrees of freedom from the pure gauge degrees of
freedom. Replacing one infinity by a flat interior leads to analogous results,
but with the reduced phase space $R^2 \cup R^2$. The utility of the results for
quantization is discussed.

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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin
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The categories of this paper are: funct-an
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The categories of this paper are: astro-ph
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: supr-con
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The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat