Inelastic Final State Interactions in B→PP Decays

A method parametrizing all inelastic final state interactions (FSI) in B→PP decays is presented (P - pseudoscalar meson). The method explicitly shows how rescattering leads to the replacement of the short-distance amplitudes with the effective quark diagram amplitudes, and how it affects the extraction of the unitarity triangle angle γ from the data. It is furthermore pointed out that the size of FSI effects cannot be determined from Bd0→K+K− decays in a satisfactory way. The case of SU(3)-violating FSI is also discussed. When fits to the branching ratios of all B→PP decays are performed with all inelastic FSI included, the extracted value of γ is shifted down by some 20o−30o when compared to the no-FSI analyses, and becomes consistent with the Standard Model value of 65o ± 7o.