High Energy Physics Seminars

ics High Energy
Wednesday, March 25, 2009
3:30 PM
HEP, Room 123
Note special room.
Hella Snoek [Host: Chris Neu]
University of Amsterdam/NIKHEF - BaBar
"Observation of the rare charmed B decay, Bd to D*+ a0-, at the BaBar experiment: On finding a needle in a haystack."
 Slideshow (PDF)
A general introduction is presented into the field of B-meson physics, the BaBar experiment, and the motivation for the branching ratio measurement of the B-meson decay Bd->D*a0. The branching ratio of this decay is sensitive to non-factorizing terms of QCD factorization, which is generally used to calculate the amplitudes of meson decays. Second, this decay can be extremely sensitive to the CKM-angle gamma, the least accurately known angle of the CKM Unitarity Triangle. An experimental challenge of this measurement is posed by the low expected branching ratio of the decay (order 10-6), in combination with the high background levels from related B-meson decays. The analysis uses more than 30 selection variables and an unbinned likelihood fit performed simultaneously in three observables. The optimization procedure of the data selection and the setup of the likelihood fit are presented in the talk. The both promising and remarkable results of the branching ratio measurement are discussed.

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