Singly Cabibbo-suppressed hadronic decays of Λ+c

Hai-Yang Cheng, Xian-Wei Kang, Fanrong Xu 2018 Phys.Rev. D 97.074028 

We study singly Cabibbo-suppressed two-body hadronic decays of the charmed baryon Λc+, namely, Λc+→ΛK+,pπ0,pη,nπ+,Σ0K+,Σ+K0. We use the measured rate of Λc+→pϕ to fix the effective Wilson coefficient a2 for naive color-suppressed modes and the effective number of color Nceff. We rely on the current-algebra approach to evaluate W-exchange and nonfactorizable internal W-emission amplitudes, that is, the commutator terms for the S wave and the pole terms for the P wave. Our prediction for Λc+→pη is in excellent agreement with the BESIII measurement. The pη (pπ0) mode has a large (small) rate because of a large constructive (destructive) interference between the factorizable and nonfactorizable amplitudes for both S and P waves. Some of the SU(3) relations such as M(Λc+→nπ+)=2M(Λc+→pπ0) derived under the assumption of sextet dominance are not valid for decays with factorizable terms. Our calculation indicates that the branching fraction of Λc+→nπ+ is about 3.5 times larger than that of Λc+→pπ0. Decay asymmetries are found to be negative for all singly Cabibbo-suppressed modes and range from -0.56 to -0.96.