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Compact Muon Solenoid
LHC, CERN

CMS-PAS-BPH-22-002
Observation of the $ \Lambda^{0}_{\mathrm{b}} \to \mathrm{J}/{\psi}\,\Xi^{-}\,\mathrm{K}^{+} $ decay
Abstract: Using pp collision data corresponding to an integrated luminosity of about 140 fb$ ^{-1} $ collected by the CMS experiment at $ \sqrt{s}= $ 13 TeV in 2016--2018, the $ \Lambda^{0}_{\mathrm{b}} \to \mathrm{J}/{\psi}\,\Xi^{-}\,\mathrm{K}^{+} $ decay is observed for the first time with a significance exceeding 5 standard deviations. The relative branching fraction, with respect to the $ \Lambda^{0}_{\mathrm{b}} \to \psi(\mathrm{2S})\,\Lambda $ decay, is measured to be $ \mathcal{B}(\Lambda^{0}_{\mathrm{b}} \to \mathrm{J}/{\psi}\,\Xi^{-}\,\mathrm{K}^{+})/\mathcal{B}(\Lambda^{0}_{\mathrm{b}} \to \psi(\mathrm{2S})\,\Lambda) = $ [ 2.5 $ \pm $ 0.8 $ \pm $ 0.9 ]%, where the first uncertainty is statistical and the second one is systematic.
CMS Publications
Compact Muon Solenoid
LHC, CERN