Production of $ϕΛ$, $D_s^{*-} Λ_c^+$, and $J/ψΛ$ in kaon-induced reactions off the nucleon

We investigate the reaction mechanism of strangeness production in $K^- p \to ϕΛ$ within a hybrid Regge approach, taking into account $t$-channel $K$- and $K^$-Reggeon exchanges. We present results for the total cross section, $t$-dependent differential cross sections, and spin-density matrix elements (SDMEs), and compare them with the available experimental data. We find that $K^$-Reggeon exchange provides the dominant contribution, while $K$-Reggeon exchange remains nonnegligible, particularly in describing the SDMEs. In contrast, the $s$-channel $Λ$ and $u$-channel nucleon exchanges are negligible. To obtain reliable predictions for the open-charm reaction $K^- p \to D_s^{-} Λ_c^+$, we employ a Quark-Gluon String Model (QGSM)-motivated Regge framework that incorporates both pseudoscalar- and vector-Reggeon exchanges. Within this framework, the Regge trajectories $α(t)$ and energy-scale parameters $s_0$ are determined consistently, thereby constaining the model and reducing theoretical ambiguities. For the hidden-charm reaction $K^- p \to J/ψΛ$, we use the same quark-level diagrammatic correspondence. The total cross sections for $K^- p \to D_s^{-} Λ_c^+$ and $K^- p \to J/ψΛ$ are suppressed by approximately 5-6 and 8-9 orders of magnitude, respectively, compared with that for $K^- p \to ϕΛ$. We also examine possible $s$-channel contributions from the hidden-charm pentaquark states with strangeness, $P_{cs}(4337)^0$ and $P_{cs}(4459)^0$, to both $D_s^{*-} Λ_c^+$ and $J/ψΛ$ production.

💡 Research Summary

The paper presents a comprehensive study of three kaon‑induced reactions on the nucleon: K⁻p → ϕΛ (strangeness production), K⁻p → Dₛ*⁻Λ_c⁺ (open‑charm production), and K⁻p → J/ψΛ (hidden‑charm production). The authors adopt a hybrid Regge approach that combines effective Lagrangian vertices with Reggeized t‑channel exchanges. For the ϕΛ channel, both pseudoscalar K‑Reggeon and vector K*‑Reggeon exchanges are included. Coupling constants for the ϕK K and ϕK* K vertices are fixed from the measured ϕ decay widths, while the meson‑baryon couplings g_{KNΛ}, g_{K* NΛ}, and κ_{K* NΛ} are taken from the Nijmegen soft‑core (NSC97a) potential. The Regge trajectories are taken in the “square‑root” form α(t)=α₀+γ