Model-Independent Analysis of $B \to \pi K$ Decays and Bounds on the Weak Phase $\gamma$

A general parametrization of the amplitudes for the rare two-body decays B -> pi K is introduced, which makes maximal use of theoretical constraints arising from flavour symmetries of the strong interactions and the structure of the low-energy effective weak Hamiltonian. With the help of this parametrization, a model-independent analysis of the branching ratios and direct CP asymmetries in the various B -> pi K decay modes is performed, and the impact of hadronic uncertainties on bounds on the weak phase gamma = arg(Vub*) is investigated.