Probing Heavier-Baryon Oscillations through Light-Baryon Mixing

Abstract

Motivated by the existing direct limits on $Ξ_b^0$ and $Ξ_c^0$ oscillations, we investigate how Standard Model weak interactions connect baryon-number-violating mixing in heavy neutral baryons to the much more strongly constrained neutron-antineutron and $Λ-\barΛ$ mixing. We focus on $Ξ_b^0$, $Λ_b^0$, $Ξ_c^0$, and $Ω_c^0$ oscillations and derive indirect constraints on their mass-mixing parameters from existing limits on $n-\bar n$ oscillations and on $Λ-\barΛ$ mixing, the latter inferred from dinucleon-decay searches. The weak baryon-to-baryon transition amplitudes are estimated by saturating the relevant hadronic correlators with low-lying intermediate baryons. The required weak vertices are modelled using semileptonic form factors from lattice QCD, quark models, and QCD sum rules. Since these form factors must be continued outside their physical semileptonic domains and the resulting loop integrals depend on a UV cutoff, our results are order-of-magnitude estimates subject to sizeable hadronic uncertainties. For a benchmark cutoff of $10~{\rm GeV}$, the indirect bounds on the $Ξ_b^0$ and $Ξ_c^0$ mixing parameters are roughly three and five orders of magnitude stronger than the direct LHCb and Belle limits, indicating that light-baryon $|ΔB|=2$ searches can probe heavy-baryon oscillations far beyond present direct sensitivities.