First Measurements of Absolute Branching Fractions of the Ξ0c Baryon at Belle

Abstract

We present the first measurements of absolute branching fractions of Ξ0c decays into Ξ−π+, ΛK−π+, and pK−K−π+ final states. The measurements are made using a dataset comprising (772±11)×106 B¯B pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB e+e− collider. We first measure the absolute branching fraction for B−→¯Λ−cΞ0c using a missing-mass technique; the result is B(B−→¯Λ−cΞ0c)=(9.51±2.10±0.88)×10−4. We subsequently measure the product branching fractions B(B−→¯Λ−cΞ0c)B(Ξ0c→Ξ−π+), B(B−→¯Λ−cΞ0c)B(Ξ0c→ΛK−π+), and B(B−→¯Λ−cΞ0c)B(Ξ0c→pK−K−π+) with improved precision. Dividing these product branching fractions by the result for B−→¯Λ−cΞ0c yields the following branching fractions: B(Ξ0c→Ξ−π+)=(1.80±0.50±0.14)%, B(Ξ0c→ΛK−π+)=(1.17±0.37±0.09)%, and B(Ξ0c→pK−K−π+)=(0.58±0.23±0.05)%. For the above branching fractions, the first uncertainties are statistical and the second are systematic. Our result for B(Ξ0c→Ξ−π+) can be combined with Ξ0c branching fractions measured relative to Ξ0c→Ξ−π+ to yield other absolute Ξ0c branching fractions.