arXiv2026
In this article, we reanalyze the mass and pole residue of $Λ$-type singly heavy baryons with spin-parity $J^P=1/2^{\pm}$ using two-point QCD sum rules. Then, we investigate the electroweak transition form factors of $Λ_b\toΛ^*_c(2595)$ and $Ξ_b\toΞ^*_c(2790)$ within the framework of three-point QCD sum rules. At the hadron side, all possible couplings of the interpolating currents to hadronic states are taken into account, while at the QCD side, both the perturbative part and vacuum condensate contributions up to dimension-8 are included. Using the obtained form factors, we calculate the decay widths and branching ratios for the semileptonic decays $Λ_b\toΛ^*_c(2595)\ell\barν_\ell$ and $Ξ_b\toΞ^*_c(2790)\ell\barν_\ell$ ($\ell=e,μ$ and $τ$), as well as for the corresponding nonleptonic decays $Λ_b\toΛ^*_c(2595)π[ρ]$, $Λ_b\toΛ^*_c(2595)K[K^*]$, $Ξ_b\toΞ^*_c(2790)π[ρ]$ and $Ξ_b\toΞ^*_c(2790)K[K^*]$. Our estimates for the branching ratios of $Λ_b\toΛ^*_c(2595)\ell\barν_\ell$ are comparable with the experimental data and other theoretical results. These results can provide valuable references for future measurements. In addition, we present predictions for several observables in these semileptonic decays, including the lepton universality ratio, the forward-backward asymmetry $A_{FB}$, and the asymmetry parameter $α$, which can provide useful references for future experiments to test the Standard Model and probe new physics beyond it.