Coupled-channel final-state interactions through Reggeon exchange for D(B)→ππ,KK̄

Coupled-channel final-state-interaction effects for D and B weak decays into ππ and KK̄ are discussed in a Regge framework. It is found that the inclusion of coupled-channel effects significantly affects the results obtained previously in a quasi-elastic approximation. It is also shown that in the isospin I=0 channel the inelastic final-state transitions (ππ)I=0→(KK̄)I=0 dramatically influence the phase of the B0→(KK̄)I=0 amplitude.