Speaker
Mr
Toshi Sumida
(Dept. of Physics, Kyoto University)
Description
The rare decay KL-> pi0 nu nubar is a Flavor Changing Neutral
Current process from strange to down quarks and
its observation is new evidence for direct CP violation. Its
irreducible theoretical uncertainty is very small and the
decay is considered an ideal place to test the Standard Model and
explore signs of new physics in quark flavor
physics.
KEK-PS E391a, performed at the KEK 12GeV proton synchrotron, is
the first dedicated experiment to measure
the branching fraction of this decay mode. The beam line is very
narrow to set the constraints on the pi0
kinematics. The detector hermetically covers the decay region to
reduce backgrounds from other decay modes
with extra particles.
We will report results of recent data analysis mainly for the
second data set (Run-II). It was carried out from
February to April in 2005 with several crucial upgrades in the
detector. Background reductions and improvements
to the sensitivity for KL-> pi0nunubar due to those upgrades of
the detector are discussed.
Primary author
Mr
Toshi Sumida
(Dept. of Physics, Kyoto University)
