Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: K Rare Decays with NA62   The long-term goal of NA62 is to measure the ultra rare K+/- -> pi+/- nu
anti-nu decay with a sensitivity of 10^-12 per event. This is done by using the
decay - in - flight technique which allows a signal acceptance of ~10% . The
aim is to collect about 100 signal events in two years of data taking with a
background to signal ratio smaller than 10%. The principle of the experimental
measurement and the layout of the detector are presented. During 2007/2008 a
dedicated run devoted to NA62 prototype tests and study of K_e2 decays was
taken. The first phase of the NA62 experiment is aiming at a high precision
test of the lepton universality by measuring the helicity suppressed ratio R_K.
The preliminary result based on 40% of the 2007 NA62 data sample, R_K =
K_e2/K_mu2 = (2.500 +/- 0.016) x 10^-5, which is the first result with a
precision better than 1%, is consistent with the Standard Model.
  Aiming at charge asymmetry measurements, the NA48/2 experiment collected an
unprecedented amount of charged K_(3 pi) events. The large samples allowed a
precision measurement of rare charged kaon decays. New measurements of the
K+/-_(pi l l) decays based on the full NA48/2 data sample collected during
2003/2004 are reported in this paper. Samples of about 7200 reconstructed K+/-
-> pi+/- e+ e- events, and more than 3000 K+/- -> pi+/- mu+ mu- events, with a
few percent background contamination, have been collected. A precise
measurement of the branching fractions and the form factors of the rare decays
K+/-_(pi l l)$ were performed. Measurements of the CP-violating and the
forward-backward asymmetries are reported.

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The categories of this paper are: econ
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The categories of this paper are: solv-int
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The categories of this paper are: physics
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The categories of this paper are: nucl-ex
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The categories of this paper are: funct-an
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The categories of this paper are: patt-sol
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The categories of this paper are: adap-org
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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: stat
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The categories of this paper are: astro-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
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The categories of this paper are: q-alg
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The categories of this paper are: chem-ph
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The categories of this paper are: chao-dyn