Search for the doubly charmed baryon Ω_cc⁺

A search for the doubly charmed baryon Ω_cc⁺ with the decay mode Ω_cc⁺ → Ξ_c⁺K⁻π⁺ is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment from 2016 to 2018, corresponding to an integrated luminosity of 5.4 fb⁻¹. No significant signal is observed within the invariant mass range of 3.6 to 4.0GeV/c². Upper limits are set on the ratio R of the production cross-section times the total branching fraction of the Ω_cc⁺ → Ξ_c⁺K⁻π⁺ decay with respect to the Ξcc++→Λc+K−π+π+ decay. Upper limits at 95% credibility level for R in the range 0.005 to 0.11 are obtained for different hypotheses on the Ω_cc⁺ mass and lifetime in the rapidity range from 2.0 to 4.5 and transverse momentum range from 4 to 15 GeV/c.