CERN Accélérateur de science

External conference: UNIVERSITE DE GENEVE

Ecole de physique
Département de physique nucléaire et corspusculaire

24, Quai Ernest-Ansermet

1211 GENEVE 4

Tél: (022) 379 62 73

Fax: (022) 379 69 92

The success of the B factories has dramatically improved our understanding of CP violation. The search for clear signs of new physics through measurements of CP violation is limited by understanding of the CKM elements |Vub| and |Vcb|. Improvement of our knowledge of the least well known CKM parameter, |Vub|, therefore directly translates to a more stringent test of the Standard Model. The prodigious samples of B meson decays available at the B factories, along with advances in the theory involving semileptonic B decays, have been used to provide a determination of both, |Vcb| and the b-quark mass, with a precision of 1%, and bring the precision of |Vub| well below 10%. The experimental and theoretical issues surrounding the determination of |Vub| and |Vcb| are complex and sometimes controversial. More recently, focus has been placed on ensuring accurate determinations of the b-quark mass using only semileptonic B decays, discarding the poorly understood radiative B decays. The use of a variety of strategies for determining these CKM matrix elements provides important cross-checks on the theoretical uncertainties that in most cases dominate the overall uncertainties of |Vub| and |Vcb|. I will present various measurements of semileptonic B decays at Belle, and how they have meshed together to provide precision measurements of the CKM matrix element |Vcb|, the b-quark mass, and a better understanding of CKM matrix element |Vub|. I will also discuss important recent developments in the approach to the inclusive determination of |Vub|, which may have resolved the ~3 sigma discrepancy with measurements of the CP violation phases, and exclusive |Vub| determinations."

Information : http://dpnc.unige.ch/seminaire/annonce.html

Organizer : J.-S. Graulich