Two-body hadronic weak decays of antitriplet charmed baryons

We study Cabibbo-favored (CF) and singly Cabibbo-suppressed (SCS) two-body hadronic weak decays of the antitriplet charmed baryons Λ + c , Ξ 0 c , and Ξ + c with more focus on the last two. Both factorizable and nonfactorizable contributions are considered in the topologic diagram approach. The estimation of nonfactorizable contributions from W -exchange and inner W -emission diagrams relies on the pole model and current algebra. The nonperturbative parameters in both factorizable and nonfactorizable parts are calculated in the MIT bag model. Branching fractions and up-down decay asymmetries for all the CF and SCS decays of antitriplet charmed baryons are presented. The prediction of B ( Ξ + c → Ξ 0 π + ) agrees well with the measurements inferred from Belle and CLEO, while the calculated B ( Ξ 0 c → Ξ − π + ) is too large compared to the recent Belle measurement. We conclude that these two Ξ c → Ξ π + modes cannot be simultaneously explained within the current-algebra framework for S -wave amplitudes. This issue needs to be resolved in future study. The long-standing puzzle with the branching fraction and decay asymmetry of Λ + c → Ξ 0 K + is resolved by noting that only the type-II W -exchange diagram contributes to this mode. We find that not only does the calculated rate agree with experiment but also the predicted decay asymmetry is consistent with the SU(3)-flavor symmetry approach in sign and magnitude. Likewise, the CF mode Ξ 0 c → Σ + K − and the SCS decays Ξ 0 c → p K − , Σ + π − proceed only through type-II W exchange. They are predicted to have large and positive decay asymmetries. These features can be tested in the near future.