Chiral partners of strange doubly heavy baryons: Mass relations and decay predictions after the 2026 LHCb discoveries
Three spectacular LHCb measurements in 2026---the observations of $Ω_{cc}^{+}$, $Ξ_{cc}^{+}$, and the beauty-strange structure $B_{s0}^{*}(5700)^0$---make possible an experimentally constrained analysis of chiral partners of strange doubly heavy baryons. The doubly charmed masses test the earlier Ma--Harada prediction and support a compact, internally S-wave $cc$ color source. We combine this comparison with the heavy-quark--diquark hyperfine relation and with chiral gaps from the theory of chiral doublers, to construct consistent $ccs$ and $bbs$ parity multiplets and a conditional extension to $bcs$. Under meson-to-baryon parity-gap transfer, the $349$ MeV input from the $D_s$ sector gives negative-parity $ccs$ targets near $4.075$ and $4.183$ GeV. The separate $332$ MeV input from the $B_s$ sector fixes the $bbs$ partner masses relative to their unknown ground-state mass, conditional on the new beauty-strange state's chiral-partner assignment. We relate the differences of hyperfine splittings in the two parity sectors of mesons and baryons, and identify equal reduced single-pion widths, an E1 reduced-width ratio $1:8:4:5$, and a kaon selection rule whose leading predictions contain no new transition parameters. Absolute widths are estimated by matching the published Bardeen--Eichten--Hill and Harada--Rho--Sasaki meson calculations to a common convention. In the reference calculation, all members of the predicted $ccs$ and $bbs$ multiplets are narrow. In the proposed $Ω_{QQ}π^0$ and $Ω_{QQ}γ$ searches at LHCb, these states are expected to produce peaks dominated by detector resolution, allowing their masses and decay patterns to be investigated even when their intrinsic widths remain unresolved. The upper charm state is above kaon threshold but protected in the spectator limit.