First Observation of Doubly Cabibbo-Suppressed Decay of a Charmed Baryon: $\hat{I}{›}_c^{+}\to p{K}^{+}\ddot{I}{€}^{-}$

Abstract

We report the first observation of the decay $\hat{I}{›}_c^{+}\to p{K}^{+}\ddot{I}{€}^{-}$ using a 980 $\mathrm{f}{\mathrm{b}}^{-1}$ 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 $\mathcal{B}(\hat{I}{›}_c^{+}\to p{K}^{+}\ddot{I}{€}^{-})/\mathcal{B}(\hat{I}{›}_c^{+}\to p{K}^{-}\ddot{I}{€}^{+})=(2.35\pm 0.27\pm 0.21)\times 10^{-3}$, where the uncertainties are statistical and systematic, respectively.

6 pages, 3 figures