Search for the doubly heavy baryon Ξ⁺_bc decaying to J/ψΞ⁺_c

A first search for the Ξ⁺_bc→J/ψΞ⁺_c decay is performed by the LHCb experiment with a data sample of proton-proton collisions, corresponding to an integrated luminosity of 9fb⁻¹ recorded at centre-of-mass energies of 7, 8, and 13TeV. Two peaking structures are seen with a local (global) significance of 4.3(2.8) and 4.1(2.4) standard deviations at masses of 6571 and 6694MeV/c², respectively. Upper limits are set on the Ξ⁺_bc baryon production cross-section times the branching fraction relative to that of the B⁺_c→J/ψD⁺_s decay at centre-of-mass energies of 8 and 13TeV, in the Ξ⁺_bc and in the B⁺_c rapidity and transverse-momentum ranges from 2.0 to 4.5 and 0 to 20GeV/c, respectively. Upper limits are presented as a function of the Ξ⁺_bc mass and lifetime.