Observation of the ${\Xi }_c^0\to p{K}^{-}$ decay and measurement of its decay asymmetry

Abstract

A search for the Cabibbo-suppressed decay ${\Xi }_c^0\to p{K}^{-}$ is performed using $pp$ collision data corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$, collected by the LHCb experiment at a centre-of-mass energy of $13\mathrm{TeV}$. The decay is observed for the first time and its branching fraction measured to be $(4.5\pm 0.5\pm 0.2\pm 0.9)\times 10^{-5}$, where the uncertainties are statistical, systematic and from the branching fraction of the normalisation channel ${\Xi }_b^{-}\to {\Xi }_c^0(\to p{K}^{-}{K}^{-}{\pi }^{+}){\pi }^{-}$. Using the decay chain ${\Xi }_b^{-}\to {\Xi }_c^0(\to p{K}^{-}){\pi }^{-}$, the decay asymmetry parameter of the ${\Xi }_c^0\to p{K}^{-}$ decay is determined to be ${\alpha }_{{\Xi }_c^0}=0.32\pm 0.15\pm 0.01$.

All figures and tables, along with any supplementary material and additional information, are available at https://lhcb-glance.cern.ch/alcm/public/analysis/full-details/6110/ (LHCb public pages)