Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: $B \to \pi \ell \nu_l$ Width and $|V_{ub}|$ from QCD Light-Cone Sum
  Rules   We employ the $B\to\pi$ form factors obtained from QCD light-cone sum rules
and 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-collaboration
measurements 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, taken
as an input for a $z$-series parameterization, yield the $q^2$-shape in the
whole semileptonic region of $B\to \pi\ell\nu_\ell$. We also present the
charged lepton energy spectrum in this decay. Furthermore, the current
situation with $B\to \tau\nu_\tau$ is discussed from the QCD point of view. We
suggest 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. The
sensitivity of this observable to new physics is illustrated by including a
charged Higgs-boson contribution in the semileptonic decay amplitude.

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The categories of this paper are: gr-qc
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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
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The categories of this paper are: acc-phys
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The categories of this paper are: cond-mat
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: astro-ph
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The categories of this paper are: physics