Potential of discovering $Ξ_{cc}^+$ in $Λ_b $ decays

TL;DR

The paper tackles the long-standing search for the doubly charmed baryon $Ξ_{cc}^+$. It proposes producing $Ξ_{cc}^+$ in the decay $Λ_b \to Ξ_{cc}^+ D^-$ and exploiting final-state interactions, especially the color-enhanced intermediate $Λ_b^0 \to Λ_c^+ π^-$, as the dominant mechanism due to suppressed short-distance contributions. Using a hadronic-amplitude framework with $M = i \overline{u}_{cc} ( A + B γ_5 ) u_b$ and inputs from lattice form factors, they obtain ${\cal B}(Λ_b \to Ξ_{cc}^+ D^-) = (5.1 ± 3.9) × 10^{-4}$ and $α = -0.18 ± 0.10$, with visible two-body-tagging rates ${\cal B}_{\rm vis}(C) ≈ (1.9 ± 1.5) × 10^{-8}$ and ${\cal B}_{\rm vis}(H) ≈ (3.5 ± 2.8) × 10^{-8}$. With about ${\cal O}(10^{12})$ produced $Λ_b$, this implies ${\cal O}(10^2)$ reconstructed events after efficiency, enabling discovery and precise mass determination; the study also outlines complementary tagging strategies and discusses prospects for observing $Ω_{cc}^+$ via related channels. Overall, the work provides a realistic, clean search channel for $Ξ_{cc}^+$ at LHCb and informs broader tests of heavy-quark dynamics.

Abstract

We propose to search for $Ξ_{cc}^+$ in the decay $Λ_b \to Ξ_{cc}^+ D^-$, which serves as a tagged and reconstructible source of $Ξ_{cc}^+$, providing an experimentally clean environment for its discovery. A possible fully charged final state is $[(pK^- K^- π^+)_{Ξ^0_c} π^ + ]_{Ξ_{cc}^+} \,(K^+ π^- π^-)_{D^-}$, where the subscripts indicate the parent hadron in the decay chain. We estimate the branching fraction to be ${\cal B}(Λ_b \to Ξ_{cc}^+ D^-) = ( 5.1 \pm 3.9) \times 10^{-4}$, while the fully charged final state corresponds to an effective branching fraction of order $10^{-8}$. These results indicate that LHCb has the potential to discover the $Ξ_{cc}^+$. The prospects for observing $Ω_{cc}^+$ are also briefly discussed.

Figures (1)

• Figure 1: The FSI diagrams for the $s$-, $t$-, and $u$-channel rescattering.