Orateur
Dr
Phillip Urquijo Urquijo
(University of Bonn)
Description
We report a search for $B$ decays into invisible final states.
The signal is identified by fully
reconstructing the accompanying $B$ meson and requiring no other
charged particles and no extra energy deposited in the calorimeter.
The upper limit obtained will be reported and the corresponding
physics will be discussed.
We report measurements of the $B \to D_{s}^{(*)} K \ell \nu$ decay
branching fractions and of the characteristics of the $D_{s}^{(*)}K$
system.
We report a measurement of $B \to \tau \nu$ decays. A sample of $B\bar B
$
pair events are tagged by reconstructing one $B$ meson decaying to
hadronic
final states. We obtain the branching fraction of $B\to\tau\nu$ and
present
a direct determination of the product of the $B$ meson decay constant $f
_{B}$
and the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $V_{ub}
$.
We also discuss constraints on the charged Higgs.
The branching fractions of the purely leptonic decays
$B^+ \to \ell^+ \nu_{\ell}$, ($\ell= e$, $\mu$) are expected to be very
small due to helicity suppression in the Standard Model. With
contributions
from new physics beyond the Standard Model, helicity suppression may be
avoided. Moreover, these modes have a very clean experimental signature.
In this study, we present a search for $B^+ \to \ell^+ \nu_{\ell}$
decays
using the hadronic $B$-meson tagging method, where a novel technique of
neural-network-based $B$-meson tagging method is applied for the optimal
background suppression.
We also report a study of the charmless semileptonic B-meson decays
$B^+ \to \eta \ell^+ \nu$ and $B^+ \to \eta^{\prime} \ell^+ \nu$, in
events
in which the decay of one $B$ meson is fully reconstructed in an
hadronic
final state.
These results are obtained from the large data sample collected at the
$\Upsilon(4S)$ resonance with the Belle detector at the KEKB
asymmetric-energy $e^+e^-$ collider.
Auteur principal
Dr
Phillip Urquijo
(University of Bonn)
