| アブストラクト: |
Charmless semileptonic B-meson decays are an excellent tool
to study the weak and strong interaction in the b quark sector.
Thanks to the wealth of data collected at B factories, it has been
possible to perform tests of the unitarity of the
Cabibbo-Kobayashi-Maskawa matrix and determine the magnitude of
the CKM matrix elements |V_{cb}| and |V_{ub}| at the 2% and 8%
level respectively.
I will discuss how various measurements of semileptonic B decays mesh
together to determine the size of |V_{ub}|, and how such measurements are
made possible through progress in the theory of B decays.
I will give an overview of various analysis techniques and
present the current status of the experimental measurements of |V_{ub}|
with inclusive and exclusive semileptonic B decays, highligthing the
precision measurements with the BABAR detector at PEP-II asymmetric-
energy B Factory at SLAC. |
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