2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/199805We present a new theoretical framework for the study of $B\to X_u \ell ν$ decays, which includes all known perturbative and non-perturbative contributions and a description of leading and subleading Fermi motion effects. The perturbative and non-perturbative regimes are separated by a ``hard'' Wilsonian cutoff $μ\sim 1$ GeV. We bring into focus some problems related to the high $q^2$ region and to Weak Annihilation effects. We provide estimates of the CKM parameter $|V_{ub}|$ using the described framework and discuss the related theoretical uncertainty.Dec 2007. 4pp. To appear in the proceedings of the 2007 Europhysics Conference on High Energy Physics (EPS-HEP2007), Manchester, England, 19-25 Jul 2007High Energy Physics - Phenomenologytext