Observation of the $B^0_s\to K^-\pi^+$, $\Lambda^{0}_b\to p\pi^{-}$ and $\Lambda^{0}_b\to p K^{-}$ Modes at CDF

We report the first observation of the charmless decays modes $B^0_s\rightarrow K^-\pi^+$, $\Lambda^{0}_b\rightarrow p\pi^{-}$, $\Lambda^{0}_b\rightarrow p K^{-}$ using 1 fb$^{-1}$ of CDF data. All three modes are expected to exhibit significant direct-$CP$~asymmetries, of which we present preliminary measurements. The new modes are separated from other larger-yield two-prong charmless modes by means of a global kinematic-PID fit, including a detailed model of QED radiation effects and non-Gaussian resolution tails.