Two-body weak decays of doubly charmed baryons

The hadronic two-body weak decays of the doubly charmed baryons Xi(++)(cc); Xi(+)(cc), and Omega(+)(cc) are studied in this work. To estimate the nonfactorizable contributions, we work in the pole model for the P-wave amplitudes and current algebra for S-wave ones. For the Xi(++)(cc) -> Xi(+)(c)pi(+) mode, we find a large destructive interference between factorizable and nonfactorizable contributions for both S- and P-wave amplitudes. Our prediction of similar to 0.70% for its branching fraction is smaller than the earlier estimates in which nonfactorizable effects were not considered, but agrees nicely with the result based on an entirely different approach, namely, the covariant confined quark model. On the contrary, a large constructive interference was found in the P-wave amplitude by Dhir and Sharma, leading to a branching fraction of order (7-16)%. Using the current results for the absolute branching fractions of (Lambda(+)(c), Xi(+)(c)) -> pK(-) pi(+) and the LHCb measurement of Xi(++)(cc) -> Xi(+)(c)pi(+) relative to Xi(++)(cc) -> Lambda(+)(c) K- pi(+)pi(+), we obtain B(Xi(++)(cc) -> Xi(+)(c)pi(+))(expt) approximate to (1.83 +/- 1.01)% after employing the latest prediction of B(Xi(++)(cc) -> Sigma(++)(c) (K) over bar*(0)). Our prediction of B(Xi(++)(cc) -> Xi(+)(c)pi(+)) approximate to 0.7% is thus consistent with the experimental value but in the lower end. It is important to pin down the branching fraction of this mode in future study. Factorizable and nonfactorizable S-wave amplitudes interfere constructively in Xi(+)(cc) -> Xi(0)(c)pi(+). Its large branching fraction of order 4% may enable experimentalists to search for the Xi(+)(cc) through this mode. That is, the Xi(+)(cc) is reconstructed through the Xi(+)(cc) -> Xi(0)(c)pi(+) followed by the decay chain Xi(0)(c) -> Xi(-)pi(+) -> p pi(-)pi(-)pi(+). Besides Xi(+)(cc) -> Xi(0)(c)pi(+), the Xi(+)(cc) -> Xi(+)(c) (pi(0), eta) modes also receive large nonfactorizable contributions to their S-wave amplitudes. Hence, they have large branching fractions among Xi(+)(cc) -> B-c + P channels. Nonfactorizable amplitudes in Xi(++)(cc) -> Xi c'(+)pi(+) and Omega(+)(cc) -> Xi(c)'(+) (K) over bar (0) are very small compared to the factorizable ones owing to the Pati-Woo theorem for the inner W-emission amplitude. Likewise, nonfactorizable S-wave amplitudes in Xi(+)(cc) -> Xi(c)'(+) (pi(0), eta) decays are also suppressed by the same mechanism.