Hadronic Mass Moments From Semileptonic B Meson Decays

1
Hadronic Mass Moments From Semileptonic B Meson
Decays


Motivation
CKM matrix describes quark mixing by relating the
weak- to the mass- eigenstates and accommodates
CP violation.
W
b
c
Semileptonic B decays give direct access to Vub
and Vcb Allow for factorization of leptonic and
hadronic currents.
No interaction between W ? l? and c-quark
Hadronic Mass Spectrum from Semileptonic B Decays
Beam Enery Substituted Mass of Fully
Reconstructed B Mesons
Operator Product Expansions connect mass moments
with HQE parameters and Vcb
perturbative expansion in as
Measure moments of mass spectrum as funtion of
minimum lepton momentum
non-perturbative expansion to first, second and
third order in 1/mB
7100 signal 2100 background


Employ Calibration Curves to correct for limited
detector resolution efficiency
Crosschecks Results from independent subsamples
Fit of OPE Calculations to measured Moments
Extract HQE parameters and Vcb
Input for Vcb extraction
OPE fit to the BABAR data

• Correction derived with
• help of calibration is
• independent of Xc model
• and branching fractions

D()p
D
OPE prediction using CLEO data only ltMx2gt and
ltE?gt from b?s?
D
D
Comparison with other determinations of Vcb
Results
Results for Hadronic Mass Moments