Observation of Cabibbo-Suppressed Two-Body Hadronic Decays and Precision Mass Measurement of the ${\Omega }_c^0$ Baryon

The first observation of the singly Cabibbo-suppressed ${\Omega }_c^0\to {\Omega }^{-}{K}^{+}$ and ${\Omega }_c^0\to {\Xi }^{-}{\pi }^{+}$ decays is reported, using proton-proton collision data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$, collected with the LHCb detector between 2016 and 2018. The branching fraction ratios are measured to be $\frac{B({\Omega }_c^0\to {\Omega }^{-}{K}^{+})}{B({\Omega }_c^0\to {\Omega }^{-}{\pi }^{+})}=[6.08\pm 0.51\left(\mathrm{stat}\right)\pm 0.40\left(\mathrm{syst}\right)]\%,\frac{B({\Omega }_c^0\to {\Xi }^{-}{\pi }^{+})}{B({\Omega }_c^0\to {\Omega }^{-}{\pi }^{+})}=[15.81\pm 0.87\left(\mathrm{stat}\right)\pm 0.44\left(\mathrm{syst}\right)\pm 0.16\left(\mathrm{ext}\right)]\%.$ In addition, using the ${\Omega }_c^0\to {\Omega }^{-}{\pi }^{+}$ decay channel, the ${\Omega }_c^0$ baryon mass is measured to be $M\left({\Omega }_c^0\right)=2695.28\pm 0.07\left(\mathrm{stat}\right)\pm 0.27\left(\mathrm{syst}\right)\pm 0.30\left(\mathrm{ext}\right)\mathrm{MeV},$ improving the precision of the previous world average by a factor of 4.