Search for the doubly heavy Ξbc0 baryon via decays to D ⁰ pK ⁻

A search for the doubly heavy Ξbc0 baryon using its decay to the D ⁰pK ^– final state is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the LHCb experiment between 2016 and 2018, corresponding to an integrated luminosity of 5.4 fb ⁻¹. No significant signal is found in the invariant mass range from 6.7 to 7.2 GeV/c ². Upper limits are set at 95% credibility level on the ratio of the Ξbc0 production cross-section times its branching fraction to D ⁰pK ⁻ relative to that of the Λb0→D0pK− decay. The limits are set as a function of the Ξbc0 mass and lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and in the transverse momentum region from 5 to 25 GeV/c. Upper limits range from 1.7 × 10 ⁻² to 3.0 × 10 ⁻¹ for the considered Ξbc0 mass and lifetime hypotheses. [Figure not available: see fulltext.]