Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A relativistic toy model for back-reaction   We consider a quantized massless and minimally coupled scalar field on a
circular closed string with a time-dependent radius $R(t)$, whose undisturbed
dynamics is governed by the Nambu-Goto action. Within the semi-classical
treatment, the back-reaction of the quantum field onto the string dynamics is
taken into account in terms of the renormalized expectation value of the
energy-momentum tensor including the trace anomaly. The results indicate that
the back-reaction could prevent the collapse of the circle $R\downarrow0$ --
however, the semi-classical picture fails to describe the string dynamics at
the turning point (i.e., possible bounce) at finite values of $R$ and $\dot R$.
The fate of the closed string after that point (e.g., oscillation or eternal
acceleration) cannot be determined within the semi-classical picture and thus
probably requires the full quantum treatment. PACS: 04.62.+v, 03.70.+k,
11.15.Kc, 04.60.-m.

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The categories of this paper are: dg-ga
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The categories of this paper are: q-alg
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The categories of this paper are: bayes-an
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
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The categories of this paper are: hep-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
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The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio