Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: State-selective influence of the Breit interaction on the angular
  distribution of emitted photons following dielectronic recombination   We report a measurement of $KLL$ dielectronic recombination in charge states
from Kr$^{+34}$ through Kr$^{+28}$, in order to investigate the contribution of
Breit interaction for a wide range of resonant states. Highly charged Kr ions
were produced in an electron beam ion trap, while the electron-ion collision
energy was scanned over a range of dielectronic recombination resonances. The
subsequent $K\alpha$ x rays were recorded both along and perpendicular to the
electron beam axis, which allowed the observation of the influence of Breit
interaction on the angular distribution of the x rays. Experimental results are
in good agreement with distorted-wave calculations. We demonstrate, both
theoretically and experimentally, that there is a strong state-selective
influence of the Breit interaction that can be traced back to the angular and
radial properties of the wavefunctions in the dielectronic capture.

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The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
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The categories of this paper are: hep-ex
5
The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: nlin