### Speaker

Dr
Gianluca Lamanna
(SNS & INFN Pisa)

### Description

The NA48/2 experiment was originally constructed to measure CP
violation in charged kaon sector, using simultaneous positive and
negative kaon beams. Several charged kaon decay modes have been
collected during two years of data taking. The kaon system is a unique
laboratory in which study the dynamics of the QCD in low energy regime,
with high statistics and precision. The pi-pi scattering close the
threshold has been studied with unprecedented statistics, using
more than one million K+- --> Pi+ Pi- e+- nu (Ke4) and the cusp
structure in more than 60 million K+- --> pi+- pi0 pi0.
The S-wave scattering lengths a0 and a2 have been measured
independently in these two modes allowing accurate tests of Chiral Perturbation
Theory.
We also report on the measurement of the branching fraction of the decay
K+- -> pi+- gamma gamma using more than 1000 reconstructed decays from
the 2003 NA48/2 data set. The data statistics are about a factor of 30
larger than for any previous measurement. The spectrum of invariant
gamma gamma mass shows the expected behaviour,
being compatible with a decay parameter c^ of the order of 2.
In addition we report on the first measurement of the related decay K+- -> pi+- e+
e- gamma (with internal gamma conversion) branching fraction and
the decay distribution, using 120 reconstructed K+- -> pi+- e+ e- gamma
events from the complete NA48/2 data set.
Both measurements are in good agreement with the theoretical
expectations from Chiral Perturbation Theory.

### Primary author

Dr
Gianluca Lamanna
(SNS & INFN Pisa)