First Observation of Doubly Cabibbo-Suppressed Decay of a Charmed Baryon: $\Lambda^+_c \rightarrow p K^+ \pi^-$

摘要: We report the first observation of the decay Λ+c→pK+π− using a 980 fb−1 data sample collected by the Belle detector at the KEKB asymmetric-energy e+e− collider. This is the first doubly Cabibbo-suppressed decay of a charmed baryon to be observed. We measure the branching ratio of this decay with respect to its Cabibbo-favored counterpart to be B(Λ+c→pK+π−)/B(Λ+c→pK−π+)=(2.35±0.27±0.21)×10−3, where the uncertainties are statistical and systematic, respectively.