Improved Constraints on $B \to \pi\ell \bar\nu_{\ell}$ Form Factors
  The behavior of the $\bpi$ form factors in the entire physical range is examined in a model independent way. Unitarity bounds are further constrained by the lattice results (APE). From this analysis, we obtain $f^{+}(0) = 0.38 \pm .03$ if the $B^{*}$-pole dominance behavior is assumed. However, to get the information on the behavior of the form factor $f^{+}$, QSR results are included. We see the deviations from the pole dominance due to the contributions of the higher singularities which are to be treated   with more precise lattice data. 
Damir Becirevic