Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonlinear Breit-Wheeler pair production in a tightly focused laser beam   The only available analytical framework for investigating QED processes in a
strong laser field systematically relies on approximating the latter as a plane
wave. However, realistic high-intensity laser beams feature much more complex
space-time structures than plane waves. Here, we show the feasibility of an
analytical framework for investigating strong-field QED processes in laser
beams of arbitrary space-time structure by determining the energy spectrum of
positrons produced via nonlinear Breit-Wheeler pair production as a function of
the background field in the realistic assumption that the energy of the
incoming photon is the largest dynamical energy in the problem. A numerical
evaluation of the angular resolved positron spectrum shows significant
quantitative differences with respect to the analogous result in a plane wave,
such that the present results will be also important for the design of upcoming
strong laser facilities aiming at measuring this process.

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The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
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The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex