Search for the doubly heavy baryons $\\it{\\Xi}_{bc}^{\\rm0}$ and $\\it{\\Omega}_{bc}^{\\rm0}$ decaying to $\\it{\\Lambda_{c}^{+}\\pi^{-}}$ and $\\it{\\Xi_{c}^{+}\\pi^{-}}$

The first search for the doubly heavy $\\it{\\Omega}_{bc}^{\\rm0}$ baryon and a search for $\\it{\\Xi}_{bc}^{\\rm0}$ baryon are performed using $pp$ collision data collected with the LHCb experiment from 2016 to 2018 at a centre-of-mass energy of $13TeV$, corresponding to an integrated luminosity of 5.2$fb^{-1}$. The baryons are reconstructed via their decays to $\\it{\\Lambda_{c}^{+}\\pi^{-}}$ and $\\it{\\Xi_{c}^{+}\\pi^{-}}$. No significant excess is found for invariant masses between 6700 and 7300$MeV/c^2$, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 2 to 20$GeV/c$. Upper limits are set on the ratio of the $\\it{\\Omega}_{bc}^{\\rm0}$ and $\\it{\\Xi}_{bc}^{\\rm0}$ production cross-section times its branching fraction to $\\it{\\Lambda_{c}^{+}\\pi^{-}}$ ($\\it{\\Xi_{c}^{+}\\pi^{-}}$) relative to that of the $\\it{\\Lambda_b^{\\rm0}}$ ($\\it{\\Xi_b^{\\rm0}}$) baryon, for different lifetime hypotheses, at $95\\%$ confidence level. The upper limits range from $0.5\\times10^{-4}$ to $2.5\\times10^{-4}$ for the $\\it{\\Omega}_{bc}^{\\rm0}\\rightarrow\\it{\\Lambda_{c}^{+}\\pi^{-}}$ ($\\it{\\Xi}_{bc}^{\\rm0}\\rightarrow\\it{\\Lambda_{c}^{+}\\pi^{-}}$) decay, and from $1.4\\times10^{-3}$ to $6.9\\times10^{-3}$ for the $\\it{\\Omega}_{bc}^{\\rm0}\\rightarrow\\it{\\Xi_{c}^{+}\\pi^{-}}$ ($\\it{\\Xi}_{bc}^{\\rm0}\\rightarrow\\it{\\Xi_{c}^{+}\\pi^{-}}$) decay, depending on the considered mass and lifetime of the $\\it{\\Omega}_{bc}^{\\rm0}$ ($\\it{\\Xi}_{bc}^{\\rm0}$) baryon.