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| | '''Excited QCD''' | | '''Excited QCD''' |
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| − | Tests of Chiral Perturbation Theory with Ke4 decays at NA48 | + | [http://www.pi.infn.it/~fantechi/Conferences/2009/Chpt.doc Tests of Chiral Perturbation Theory with Ke4 decays at NA48] |
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| − | The NA48/2 experiment at the CERN SPS has accumulated more than one
| + | [http://www.pi.infn.it/~fantechi/Conferences/2009/pipi0gamma.doc Precision measurement of photon emission in K+- -> pi+- pi0 gamma decays |
| − | million
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| − | K+- --> Pi+ Pi- e+- nu (Ke4) rare decays. Such decays are a unique
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| − | laboratory to
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| − | study Pi Pi scattering close to threshold.
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| − | The S-wave scattering lengths a0 and a2 in the isospin states I=0 and
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| − | I=2 are measured
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| − | with an unprecedented experimental precision of few percents,
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| − | allowing accurate tests of
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| − | Chiral Perturbation Theory predictions of similar precision.
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| − | Using recent theoretical refinements related to isospin symmetry
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| − | breaking mass effects,
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| − | the extracted values confirm the most elaborated theoretical
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| − | predictions:
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| − | a0 = 0.220 +- 0.005 and a2 = -0.0444 +- 0.0010.
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| − | The hadronic form factors of the decay and their energy variation are
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| − | measured with an
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| − | improved precision of 5-10 percents which will allow precise
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| − | comparison with different
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| − | model predictions.
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| − | Precision measurement of photon emission in K+- -> pi+- pi0 gamma decays
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| − | We report our final result on the measurement of direct photon
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| − | emisson (DE) in the decay K+- -> pi+- pi0 gamma and its interference
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| − | (INT) with the inner bremsstrahlung amplitude. For this measurement
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| − | the full NA48/2 data set with about 600k reconstructed K+- -> pi+-
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| − | pi0 gamma decays was analyzed, which is factor of 30 larger than for
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| − | previous experiments and a factor of three w.r.t. our preliminary
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| − | result.
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| − | From this, the sizes of both the DE and the INT amplitudes have been
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| − | measured with high precision, with the INT amplitude being observed
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| − | for the first time.
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| − | In addition, the CP violating asymmetry between K+ and K- has been
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| − | obtained to be less than 10?3 in this channel.
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| | '''Moriond QCD''' | | '''Moriond QCD''' |
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| − | Precision measurement of photon emission in K+- -> pi+- pi0 gamma decays | + | [http://www.pi.infn.it/~fantechi/Conferences/2009/pipi0gamma.doc Precision measurement of photon emission in K+- -> pi+- pi0 gamma decays |
| − | ========================================================================
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| − | We report our final result on the measurement of direct photon emisson (DE) in the decay K+- -> pi+- pi0 gamma and its interference (INT) with the inner bremsstrahlung amplitude. For this measurement the full NA48/2 data set with about 600k reconstructed K+- -> pi+- pi0 gamma decays was analyzed, which is factor of 30 larger than for previous experiments and a factor of three w.r.t. our preliminary result.
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| − | From this, the sizes of both the DE and the INT amplitudes have been measured with high precision, with the INT amplitude being observed for the first time.
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| − | In addition, the CP violating asymmetry between K+ and K- has been obtained to be less than 10?3 in this channel.
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| − | Measurement of the FCNC decays K+- -> pi+- l+ l-
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| − | ================================================
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| − | We report on precise measurements of the branching fractions and the form factors of the rare decays K+- -> pi+- e+ e- and K+- -> pi+- mu+ mu-. The full NA48/2 data set was analyzed, leading to more than 7200 reconstructed events in the electronic and more than 3000 events in the muonic channel, the latter exceeding the total existing statistics by a factor of five. For both channels the selected events are almost background-free.
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| − | From these events, we have determined the branching fractions and form factors of the decays using different theoretical models. Our results of the two channels are in good agreement with each other and improve the existing world averages significantly.
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| − | In addition, we measured the CP violating asymmetry between K+ and K- in this channel to be less than a few percent.
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| | + | [http://www.pi.infn.it/~fantechi/Conferences/2009/piee-pimumu.doc Measurement of the FCNC decays K+- -> pi+- l+ l- |
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