Speaker
Dr
Marco Dreucci
(LNF- INFN)
Description
The study of radiative $K_L$ decays offers the possibility to obtain
informations on kaon structure and to test predictions of the Chiral
Perturbation Theory. Two different processes contribute to photon
emission in $K_L \rightarrow \pi e \nu \gamma$ decay
($K_{Le3\gamma}$): the inner
bremsstrahlung (IB) and the direct emission (DE). The latter is
due to photon
radiation from
intermediate hadronic states.
To compare with theoretical predictions and present best experimental
results, we measured the ratio $R = BR(K_{Le3\gamma}; E^{\ast} >
30 {\rm MeV},
\theta^*>20^{\circ})
/BR(K_{Le3})$, where $E^{\ast}$ and $\theta^{\ast}_{e\gamma}$ are
the photon energy and
the angle between electron and photon in
$K_L$ rest frame, respectively. With these cuts the theoretical
predictions for $R$
range between 0.95\% and 0.99\% . The DE contribution is expected to
be less than 1\% of IB one.
KLOE measurement benefits of the tagging technique, which
consists of
identifying $K_L$ decays through the selection of $K_S
\rightarrow \pi^+\pi^-$ decay
near the
$e^+e^-$ interaction point. This strategy allows to achieve an
optimal background
rejection, and also to measure $K_L$ momentum with good precision.
We present the results of this analysis, based on 330 pb$^{-1}$
of data acquired
during years 2001 and 2002.
Primary author
Collaboration KLOE
(INFN/LNF)
