ar X iv : h ep - p h / 06 12 35 3 v 1 2 8 D ec 2 00 6 Hadronic B decays

Many observables at the B factories are connected with branching fractions, CP asymmetries and polarization of exclusive, hadronic B decays. They provide access to the flavour and spin structure of the weak interaction, but a straightforward interpretation is usually obscured by the strong interaction. In technical terms, the difficult (long-distance) part of the strong interaction resides in the matrix elements 〈f |Oi|B̄〉, where Oi is an operator in the effective weak interaction Lagrangian. Systematic approaches to hadronic B decays are based on expansions in small parameters. The two available options exploit approximate flavour symmetries (expansion parameter mq/Λ, mq a light quark mass), or the large energy transfer in B decays (expansion parameter Λ/mb), resulting in two frameworks – “SU(3)” and “Factorization” – that could hardly be different methodically and technically. In practice, both frameworks are implemented only at the leading order, and additional assumptions are usually necessary (neglecting “small” amplitudes; estimating Λ/mb corrections). Despite this restriction, there has been much progress by applying and working out these theories over the past few years. In the following I focus on the factorization approach. Furthermore, f will be assumed to be a charmless, two-body, meson final state; the mesons are assumed to be pseudoscalar or vector mesons from the ground state nonet.