Heavy-to-light meson transitions in QCD

Summary

I discuss QCD sum rules determinations of the form factors governing the decay B→π(π)ℓν. For some of these form factors the computed dependence on the momentum transferred does not agree with the expectation from the nearest pole dominance hypothesis. Relations are observed among the form factors, that seem to be compatible with equations recently derived by Stech. The measurement of a number of colour-suppressed non-leptonic B decay rates could shed light on the accuracy of the calculation of these form factors and on the factorization approximation.