Orateur
Dr
Remi Louvot
(EPFL, Lausanne)
Description
Using fully reconstructed mesons, we measure the
branching fractions for the decays of exclusively. Assuming these decay modes
saturate decays to CP-even final states, the branching fraction
determines the relative width difference between the -odd and
-even states.
We study the decay , . In
this sample mesons are produced in three decays:
, and
, where the mesons decay to .
We determine the absolute branching fraction of the decay
, which is an important mode for measuring
the CP violating phase in the mixing.
The latter is of particular interest as it is sensitive to physics
beyond the Standard Model.
We also report the first observation of and
first evidence for , which are CP-eigenstate
decay modes. We measure the branching fractions
with a significance of
,
and with a
significance of .
The last error listed is due to uncertainty in the number of produced
pairs.
We have also performed the first search for charmed baryonic
decay, .
The measurement precision of the branching fraction at Belle is
limited by the poor knowledge of the production fraction,
.
We present the status of the current measurements and discuss their main
limitations. Using dilepton events, a new independent measurement of
is presented, together with its impact on the precision of Belle's
measurements.
We present a measurement of the CP violation parameter sin2 at
the (5S) resonance using a new tagging method called the
B- tagging. This method in general uses a (5S) decay to
a charged B meson, a neutral B meson, and a charged pion. The neutral
B meson decays to a CP eigenstate, and the charged B meson is
reconstructed
as missing mass of the neutral B meson and the charged pion. The initial
flavor of the neutral B meson is determined by the charge of the pion at
the moment of the (5S) decay. CP violating parameters can be
derived from asymmetry of the number of BB and BB events
without measuring decay time. Since the B- tagging method have
different systematic errors from the analyses on the (4S)
resonance and thus complementary. In this analysis, the neutral B meson
is reconstructed as J/ K .
All these results are based on a data sample
collected with the Belle detector at the resonance
with an integrated luminosity of 121.4 fb at the KEKB
asymmetric-energy collider.
Auteur principal
Dr
Remi Louvot
(EPFL, Lausanne)