QCD sum rules on the light cone and B -> pi form factors

The 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.