HQET and exclusive B-decays

HQET and Exclusive B Decays

Exclusive semileptonic B decays are discussed. The emphasis is on using semileptonic decays to determine |Vub| and |Vcb|. Recent progress in our understanding of B semileptonic decays to excited charmed mesons is also reviewed. Work supported in part by the U.S. Dept. of Energy under Grant No. DE-FG03-92-ER40701.

Systematics of exclusive B decays.

Charmless Exclusive Baryonic B Decays

We present a systematical study of two-body and three-body charmless baryonic B decays. Branching ratios for two-body modes are in general very small, typically less than 10−6, except for the decays with a ∆ resonance in the final state. For example, the branching ratio of the tree-dominated decay B− → p∆̄−− can be as large as 6× 10−6, and the penguin-dominated decay B− → Σ+∆̄−− is at the level o...

Exclusive Radiative B Meson Decays

We have investigated exclusive, radiative B meson decays to charmless mesons (ρ, ω, φ, K(892), K 2 (1430)) in 9.7× 106 BB̄ decays accumulated with the CLEO detector. The B → K(892)γ branching fractions are determined to be B(B0 → K∗0(892)γ) = (4.55 +0.72 −0.68 ± 0.34)×10−5 and B(B+ → K∗+(892)γ) = (3.76 +0.89 −0.83 ± 0.28)×10−5. We have searched for CP asymmetry in B → K(892)γ decays and measure ...

|Vub| from exclusive B and D decays.

We propose a model-independent method to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |Vub| from exclusive B and D decays. Combining information obtainable from B → ρ l ν̄l, B → K∗ ν ν̄, D → ρ l̄ νl and D → K∗ l̄ νl, a determination of |Vub| is possible, with an uncertainty from theory of around 10%. Theoretical uncertainties in the B → K∗ l l̄ decay rate are discussed. ∗W...