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We employ the $B\to\pi$ form factors obtained from QCD light-cone sum rulesand calculate the $B\to \pi \ell \nu_l$ width ($\ell=e,\mu$) in units of$1/|V_{ub}|^2$, integrated over the region of accessible momentum transfers,$0\leq q^2\leq 12.0 ~GeV^2$. Using the most recent BABAR-collaborationmeasurements we extract $|V_{ub}|=(3.50^{+0.38}_{-0.33}\big|_{th.}\pm 0.11\big|_{exp.})\times 10^{-3}$. The sum rule results for the form factors, takenas an input for a $z$-series parameterization, yield the $q^2$-shape in thewhole semileptonic region of $B\to \pi\ell\nu_\ell$. We also present thecharged lepton energy spectrum in this decay. Furthermore, the currentsituation with $B\to \tau\nu_\tau$ is discussed from the QCD point of view. Wesuggest to use the ratio of the $B\to \pi \tau\nu_\tau$ and $B\to \pi\ell \nu_l~(\ell =\mu,e) $ widths as an additional test of Standard Model. Thesensitivity of this observable to new physics is illustrated by including acharged Higgs-boson contribution in the semileptonic decay amplitude.

$B \to \pi \ell \nu_l$ Width and $|V_{ub}|$ from QCD Light-Cone Sum Rules