We develop the perturbative QCD formalism including Sudakov effects for semi-leptonic B meson decays. We evaluate the differential decay rate of B→πlν, and find that the perturbative calculation is reliable for the energy fraction of the pion above 0.3. Combining predictions from the soft pion theorems, we extract the value of the matrix element ∣Vub∣ which is roughly 2.7×10−3.
@article{arxiv.hep-ph/9409313,
title = {Extraction of $V_{ub}$ from the Decay $B\to \pi l \nu$},
author = {Hsiang-nan Li and Hoi-Lai Yu},
journal= {arXiv preprint arXiv:hep-ph/9409313},
year = {2010}
}