Speaker
Dr
Ermanno Imbergamo
(Universita' di Perugia)
Description
The NA48/2-Experiment at the CERN SPS has recorded more than 2
billion
charged kaon decays. From a sub-sample of this data set we have
selected
about 2 x 10^5 practically background free events of the decay
K+- -> pi+- pi0
gamma, which is an order of magnitude more than from any previous
experiment. The decay K+- -> pi+- pi0 gamma is dominated by Inner
Bremsstrahlung (IB) of the K+- -> pi+- pi0 decay, but also
exhibits a
contribution of Direct Emission (DE), which is of high
theoretical interest, as well
as the interference between both amplitudes. We present a precise
measurement of both the DE amplitude and the interference between
IB and
DE.
In addition, using the full data set, we have made the first
observation of the
very rare decay K+- -> pi+- gamma e+ e-, which has large
contributions from
higher order pion loops. We have measured the branching fraction
and the
form factor of this decay.
Finally, from 2002 data set the weak radiative decay Xi0 ->
Lambda e+ e-has
been detected for the first time. From 412 candidates in the
signal region, with
an estimated background of 15 events, the branching ratio is
measured and is
consistent with an internal bremsstrahlung process. The decay
asymmetry
parameter is also determined, consistent with that of
Xi0 -->Lambda gamma which has been measured as well.
Primary author
Dr
Ermanno Imbergamo
(Universita' di Perugia)
