Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scalar Field Green Functions on Causal Sets   We examine the validity and scope of Johnston's models for scalar field
retarded Green functions on causal sets in 2 and 4 dimensions. As in the
continuum, the massive Green function can be obtained from the massless one,
and hence the key task in causal set theory is to first identify the massless
Green function. We propose that the 2-d model provides a Green function for the
massive scalar field on causal sets approximated by any topologically trivial 2
dimensional spacetime. We explicitly demonstrate that this is indeed the case
in a Riemann normal neighbourhood. In 4-d the model can again be used to
provide a Green function for the massive scalar field in a Riemann normal
neighbourhood which we compare to Bunch and Parker's continuum Green function.
We find that the same prescription can also be used for deSitter spacetime and
the conformally flat patch of anti deSitter spacetime. Our analysis then allows
us to suggest a generalisation of Johnston's model for the Green function for a
causal set approximated by 3 dimensional flat spacetime.

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The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: stat
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The categories of this paper are: cond-mat
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: ao-sci