Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hawking radiation with dispersion versus breakdown of WKB   Inspired by the condensed matter analogues of black holes (a.k.a. dumb
holes), we study Hawking radiation in the presence of a modified dispersion
relation which becomes super-luminal at large wave-numbers. In the usual
stationary coordinates $(t,x)$, one can describe the asymptotic evolution of
the wave-packets in WKB, but this WKB approximation breaks down in the vicinity
of the horizon, thereby allowing for a mixing between initial and final
creation and annihilation operators. Thus, one might be tempted to identify
this point where WKB breaks down with the moment of particle creation. However,
using different coordinates $(\tau,U)$, we find that one can evolve the waves
so that WKB in these coordinates is valid throughout this transition region --
which contradicts the above identification of the breakdown of WKB as the cause
of the radiation. Instead, our analysis suggests that the tearing apart of the
waves into two different asymptotic regions (inside and outside the horizon) is
the major ingredient of Hawking radiation.

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The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
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The categories of this paper are: eess
7
The categories of this paper are: hep-th