  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.
