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

We report the first observation of the decay $\Lambda^{ +}_{ c} \rightarrow p K^{ +} \pi^{ -}$ using a 980 $\mathrm{ fb^{ -1}}$ 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 $\mathcal{ B}(\Lambda^{ +}_{ c} \rightarrow p K^{ +} \pi^{ -})/\mathcal{ B}(\Lambda^{ +}_{ c} \rightarrow p K^{ -} \pi^{ +})=(2.35\pm0.27\pm0.21)\times10^{ -3}$, where the uncertainties are statistical and systematic, respectively.

Categories: hep-ex