Semileptonic decays $B\to(π,ρ)eν$ in relativistic quark model

Abstract

Quark model results for the $B\to π,ρ$ decays are analysed, making use of the dispersion formulation of the model: The form factors at $q^2>0$ 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 $Γ(\bar B^0\toπ^+e\barν)=(7\pm2)\times10^{12}|V_{ub}|^2\; s^{-1}$, $Γ(\bar B^0\toρ^+e\barν)/Γ(\bar B^0\toπ^+e\barν)=1.45\pm0.1$, and $Γ_L/Γ_T=0.7\pm0.08$ are found. The effects of the constituent quark transition form factor are briefly discussed.