2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/185422The semileptonic decay B -> pi l nu is one of the most important reactions for the determination of the CKM matrix element |V_{ub}|. However, in order to extract |V_{ub}| from data one needs an accurate theoretical calculation of the hadronic matrix element describing the B to pi transition. QCD sum rules, based on operator-product expansion on the light-cone, provide a reliable approach to this aim. QCD corrections and higher twist contributions can be taken systematically into account.5 pages, talk given by S. Weinzierl at the UK Phenomenology Workshop on Collider Physics, Durham, 19-24 SeptemberHigh Energy Physics - Phenomenologytext