Factorization and hadronic B decays in the heavy quark limit

Abstract

Recent theoretical investigations (Beneke M et al 1999 Phys. Rev. Lett. 83 1914) of two-body hadronic B decays have provided justification, at least to order αs, for the use of the factorization ansatz to evaluate the B decay matrix elements provided the decay meson containing the spectator quark is not heavy. Although data is now available on many charmless two-body B decay channels, it is so far not very precise with systematic and statistical errors in total of the order of 25% or greater. Analyses have been made on ππ and πK channels with somewhat contradictory results (Beneke M et al 2001 Nucl. Phys. B 606 245; Ciuchini M et al 2001 Preprint hep-ph/0110022). We take an overview of these channels and of other channels containing vector mesons. Because factorization involves many poorly known soft QCD parameters, and because of the imprecision of the current data, we present simplified formulae for a wide range of B decays into the lowest mass pseudoscalar and vector mesons. These formulae, valid in the heavy quark limit, involve a reduced set of soft QCD parameters and, although resulting in some loss of accuracy, should still provide an adequate and transparent tool with which to confront data for some time to come. Finally we confront these formulae with the data on 19 channels. We find a plausible set of soft QCD parameters that, apart from three pseudoscalar vector channels, fit the branching ratios and the recently measured value of sin(2β) quite well.