Dispersion relations and rescattering effects in B nonleptonic decays - art. no. 074016

Recently, the final state strong interactions in nonleptonic B decays were investigated in a formalism based on hadronic unitarity and dispersion rela tions in terms of the off-shell mass squared of the B meson. We consider a heuristic derivation of the dispersion relations in the mass variables usin g the reduction Lehmann-Symanzik-Zimmermann formalism and find a discrepanc y between the spectral function and the dispersive variable used in recent works. The part of the unitarity sum which describes final state interactio ns is shown to appear as a spectral function in a dispersion relation based on the analytic continuation in the mass squared of one final particle. As an application, by combining this formalism with Regge theory and SU(3) fl avor symmetry we obtain constraints on the tree and the penguin amplitudes of the decay B-o-->pi(+)pi(-). [S0556-2821(99)04817-1].