An observation of Cabibbo-suppressed decays $\Lambda_b^0\to\Lambda_c^+K^-$ at CDF

Using $\sim 360$~pb$^{-1}$ of Run~II data collected by the CDF detector, we reconstruct the Cabibbo-suppressed decay $\Lambda_b^0\to \Lambda_c^+K^-$, followed by $\Lambda_c^+\to p^+K^- \pi^+$. The main background to this decay is the Cabibbo-allowed decay $\Lambda_b^0\to\Lambda_c^+\pi^-$, and the yields for both are obtained simultaneously from the same data sample.