Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Precision Spectroscopy of Pionic Atoms: From Pion Mass Evaluation to
  Tests of Chiral Perturbation Theory   Preliminary results of the strong interaction shift and width in pionic
hydrogen ($\pi H$) using an X-ray spectrometer with spherically bent crystals
and CCDs as X-ray detector are presented. In the experiment at the Paul
Scherrer Institute three different $(np\to 1s)$ transitions in $\pi H$ were
measured. Moreover the pion mass measurement using the $(5 \to 4)$ transitions
in pionic nitrogen and muonic oxygen is presented

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The categories of this paper are: cond-mat
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The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
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The categories of this paper are: math
22
The categories of this paper are: chao-dyn
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The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
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The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol