Measurement of branching fractions of Λc+-pK0SK0S and Λc+-pK0Sη at Belle

We present a study of a singly Cabibbo-suppressed decay A+c -pK0SK0S and a Cabibbo-favored decay A+c -pK0St7 based on 980 fb-1 of data collected by the Belle detector, operating at the KEKB energy-asymmetric e+e- collider. We measure their branching fractions relative to A+c -pK0S: B(A+c -pK0SK0S)=B(A+c -pK0S) = (1.48 +/- 0.08 +/- 0.04) x 10-2 and B(A+c -pK0St7)=B(A+c -pK0S) = (2.73 +/- 0.06 +/- 0.13) x 10-1. Combining with the world average B(A+c -pK0S), we have the absolute branching fractions, B(A+c -pK0SK0S) = (2.35 +/- 0.12 +/- 0.07 +/- 0.12) x 10-4 and B(A+c -pK0St7) = (4.35 +/- 0.10 +/- 0.20 +/- 0.22) x 10-3. The first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the uncertainty on B(A+c -pK0S). The mode A+c -pK0 SK0S is observed for the first time and has a statistical significance of > 10 sigma. The branching fraction of A+c -pK0St7 has been measured with a threefold improvement in precision over previous results and is found to be consistent with the world average.

Automated summary

We present a study of the decays A+c -pK0SK0S and A+c -pK0St7 and measure their branching fractions relative to A+c -pK0S. The absolute branching fractions are also calculated by combining with the world average. The mode A+c -pK0 SK0S is observed for the first time with a statistical significance of > 10 sigma, and the branching fraction of A+c -pK0St7 is found to be consistent with the world average with improved precision.