Charmless exclusive B decays

M. Beneke (TUM) / C.-D. Lü (IHEP)


 Exclusive decays of B mesons provide many insights into flavour-changing interactions and CP
violation, as well as strong-interaction dynamics. This is particularly true for the purely hadronic
final states of mesons without charm due to their large variety of different final states. The
theoretical challenge is to provide reliable computations of the decay characteristics, such as
branching fractions, asymmetries, polarization fractions and angular distributions. Within the
factorization framework, which relies on the large mass of the b-quark, this is accomplished by
reducing the decay amplitude to short-distance factors and simpler (though not always simple),
long-distance matrix elements. With the increasing precision of measurements, the systematic
inclusion of electromagnetic corrections is also of interest. This project aims on the one hand at
extending the scope of the theoretical framework to cover more final states, at improving its
precision by addressing power-suppressed effects in the heavy quark mass, and by including
electromagnetic effects. On the other hand, there is a need for up-to-date predictions in view the
LHCb experiment upgrade and, in particular, the new Belle II experiment, which started data taking
recently, due their capability of measuring large sets of final states, including those containing
neutral particles, with high statistics.