A technique for folding the finite decay widths of unstable final-state mesons into flavor-SU(3) amplitude analyses of two-body nonleptonic charm decays (D->PP, D->PV). Standard fits extract universal flavor-flow amplitudes assuming stable asymptotic final states; when a resonance width is comparable to the available phase space this can bias predictions. Using the optical theorem and S-matrix unitarity, the decay rate is related to the imaginary part of a forward-scattering loop with propagators cut in the narrow-width approximation. Extracted amplitudes change little, but predicted branching ratios shift most for phase-space-restricted modes (e.g. D0->K*0 eta-prime, Ds+->rho+ eta-prime).
Girish Kumar, Sudheer Muhammad, and Alexey A. Petrov (University of South Carolina) develop a technique for including finite-width effects of final-state mesons in amplitude analyses of two-body nonl…