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 Lambda(+)(c), Xi(0)(c) and Xi(+)(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 (Xi(+)(c) -> Xi(0)pi(+)) agrees well with the measurements inferred from Belle and CLEO, while the calculated B(Xi(0)(c) -> Xi(-)pi(+)) is too large compared to the recent Belle measurement. We conclude that these two Xi(c) -> Xi pi(+) 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 Lambda(+)(c) -> Xi K-0(+) 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 Xi(0)(c) -> Sigma K-+(-) and the SCS decays Xi(0)(c) -> pK(-), Sigma(+)pi(-) 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.