Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Horizon constraints and black hole entropy   To ask a question about a black hole in quantum gravity, one must restrict
initial or boundary data to ensure that a black hole is actually present. For
two-dimensional dilaton gravity, and probably a much wider class of theories as
well, the imposition of a "stretched horizon" constraint alters the algebra of
symmetries at the horizon, introducing a central term. Standard conformal field
theory techniques can then then be used to obtain the asymptotic density of
states, reproducing the Bekenstein-Hawking entropy. The microscopic states
responsible for black hole entropy can thus be viewed as "would-be pure gauge"
states that become physical because the symmetry is altered by the requirement
that a horizon exist.

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The categories of this paper are: chem-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: astro-ph
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The categories of this paper are: nlin
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The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
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The categories of this paper are: patt-sol
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
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The categories of this paper are: econ
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The categories of this paper are: hep-ph
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: ao-sci