Abstract :
Quark model results for the B → π, ϱ decays are analysed, making use of the dispersion formulation of the model: The form factors at q2 > 0 are expressed as relativistic invariant double spectral representation over invariant masses of the initial and final mesons through their light-cone wave functions. The dependence of the results on the quark model parameters is studied. For various versions of the quark model the ranges Γ(B0 → π+eν) = (7 ± 2) × 1012|Vub|2 s−1, Γ(B0 → ϱ+eν)Γ(B0 → π+eν) = 1.45 ± 0.1, and ΓLΓT = 0.7 ± 0.08 are found. The effects of the constituent quark transition form factor are briefly discussed.
