Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scattering amplitudes from finite-volume spectral functions   A novel proposal is outlined to determine scattering amplitudes from
finite-volume spectral functions. The method requires extracting smeared
spectral functions from finite-volume Euclidean correlation functions, with a
particular complex smearing kernel of width $\epsilon$ which implements the
standard $i\epsilon$-prescription. In the $L \to \infty$ limit these smeared
spectral functions are therefore equivalent to Minkowskian correlators with a
specific time ordering to which a modified LSZ reduction formalism can be
applied. The approach is presented for general $m \to n$ scattering amplitudes
(above arbitrary inelastic thresholds) for a single-species real scalar field,
although generalization to arbitrary spins and multiple coupled channels is
likely straightforward. Processes mediated by the single insertion of an
external current are also considered. Numerical determination of the
finite-volume smeared spectral function is discussed briefly and the interplay
between the finite volume, Euclidean signature, and time-ordered
$i\epsilon$-prescription is illustrated perturbatively in a toy example.

26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
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The categories of this paper are: eess
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The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
37
The categories of this paper are: supr-con
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The categories of this paper are: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: astro-ph