Speaker
Description
This talk presents a hadronic rescattering approach to final-state interactions (FSIs), with emphasis on the two-body nonleptonic decays (\Lambda_b^0\to pK^-,p\pi^-,p\rho^-,pK^{*-}). Short-distance weak amplitudes are evaluated in naive factorization. Long-distance contributions arise from intermediate hadrons rescattering into the final state through hadron exchange. Strong vertices are constructed from effective hadronic Lagrangians, and full triangle-loop integrals yield both real and imaginary parts of the amplitudes and the strong phases needed for CP asymmetries. The cutoff parameters for rescattering contributions involving charmed and charmless intermediate states are constrained by (pK^-) and (p\pi^-) data. We discuss branching fractions and helicity-dependent CP observables, including partial-wave cancellations that suppress the total CP asymmetries in these modes and the prediction of a sizable CP asymmetry in (p\rho^-). We then extend the framework to (\Lambda_b^0\to P_c^+h^-) ((h=\pi,K)), treating (P_c(4312)), (P_c(4440)) and (P_c(4457)) as hadronic molecular candidates. We present predictions of percent-level direct CP asymmetries in the pion modes and discuss the sensitivity of the kaon-mode branching fractions to pentaquark spin assignments. Finally, we briefly discuss (\bar B^0_{(s)}\to\Lambda_c^+\bar{\Lambda}_c^-), where the same cutoff parameters yield branching fractions compatible with measurements and predictions for CP asymmetries and polarization.
