Measurements of the branching fractions of Ξ plus c → Σ+K0S, Ξ+c → Ξ0π+, and Ξ plus c → Ξ0K+at Belle and Belle II

Using 983.0 fb-1 and 427.9 fb-1 data samples collected with the Belle and Belle II detectors at the KEKB and SuperKEKB asymmetric energy e+ e- colliders, respectively, we present studies of the Cabibbo-favored Xi+c decays Xi+c -> Sigma+ K0S and Xi+c -> Xi 0 pi+, and the singly Cabibbo-suppressed decay Xi+c -> Xi 0K+. The ratios of branching fractions of Xi+c -> Sigma+ K0S and Xi+c -> Xi 0K+ relative to that of Xi+c -> Xi- pi+ pi+ are measured for the first time, while the ratio B(Xi+c -> Xi 0p+)/B(Xi+c -> Xi- pi+ pi+) is also determined and improved by an order of magnitude in precision. The measured branching fraction ratios are B(Xi+c -> Sigma+ K0S) B(Xi+c -> Xi-p+ p+) = 0.067 +/- 0.007 +/- 0.003, B Xi+c -> Xi 0 pi+) B(Xi+c -> Xi-pi+ pi+) = 0.251 +/- 0.005 +/- 0.010, B(Xi+c -> Xi 0K+) B(Xi+c -> Xi-pi+ pi+) = 0.017 +/- 0.003 +/- 0.001. Additionally, the ratio B(Xi+c -> Xi 0K+)/B(Xi+c -> Xi 0 pi+) is measured to be 0.068 +/- 0.010 +/- 0.004. Here, the first and second uncertainties are statistical and systematic, respectively. Multiplying the ratios by the branching fraction of the normalization mode, B(Xi+c -> Xi- pi+ pi+) = (2.9 +/- 1.3)%, we obtain the following absolute branching fractions B(Xi+c -> Sigma+ K0S) = (0.194 +/- 0.021 +/- 0.009 +/- 0.087)%, B(Xi+c -> Xi 0p+) = (0.728 +/- 0.014 +/- 0.027 +/- 0.326)%, B(Xi+c -> Xi 0K+) = (0.049 +/- 0.007 +/- 0.003 +/- 0.022)%, where the third uncertainties are from B(Xi+c -> Xi- pi+pi+).