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

TL;DR

This work develops a hybrid Regge framework to study kaon-induced production off the nucleon, applying Reggeized $t$-channel exchanges for strangeness: $K$ and $K^*$, and extending the same mechanism to open- and hidden-charm channels via $D$, $D^*$, and $J/\psi$ Reggeons within a QGSM-motivated scheme. The Regge trajectories $\alpha(t)$ are treated as square-root forms with energy-scale parameters $s_0$ fixed consistently from diagonal transitions, reducing model ambiguities. The strangeness channel $K^- p \to \phi \Lambda$ is found to be dominated by $K^*$-Reggeon exchange, with $K$-Reggeon contributing to SDMEs, while $s$- and $u$-channel exchanges are negligible. Open- and hidden-charm channels, $K^- p \to D_s^{*-}\Lambda_c^+$ and $K^- p \to J/\psi\Lambda$, are significantly suppressed by roughly $5$–$6$ and $8$–$9$ orders of magnitude relative to the $\phi\Lambda$ channel, mainly due to larger energy scales and weaker couplings in the charm sector. The study also examines possible $s$-channel pentaquark contributions ($P_{cs}(4337)^0$ and $P_{cs}(4459)^0$); while open-charm signals are challenging to observe due to nonresonant backgrounds, the hidden-charm channel $J/\psi\Lambda$ may exhibit noticeable enhancements near threshold, depending on the $J^P$ assignments and BRs. These results provide robust benchmarks for upcoming kaon-beam experiments at J-PARC and complement existing PANDA program predictions, offering a coherent framework to explore strangeness, open-charm, hidden-charm production and potential pentaquark states in kaon-induced reactions.

Abstract

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.

Figures (13)

• Figure 1: Quark diagrams for (a) $K^- p \to \phi \Lambda, D_s^{*-} \Lambda_c^+$ and (b) $K^- p \to \phi \Lambda, J/\psi \Lambda$ in the $t$ channel.
• Figure 2: Feynman diagrams for (a) $t$-channel $K$- and $K^*$-Reggeon exchanges for $K^- p \to \phi \Lambda, J/\psi \Lambda$, and (b) $t$-channel $D$- and $D^*$-Reggeon exchanges for $K^- p \to D_s^{*-} \Lambda_c^+$.
• Figure 3: Feynman diagrams for $K^- p \to \phi \Lambda$: (a) $\Lambda$ exchange in the $s$ channel and (b) nucleon exchange in the $u$ channel.
• Figure 4: Feynman diagram for the $K^- p \to D_s^{*-} \Lambda_c^+$, $J/\psi \Lambda$ reactions via $s$-channel $P_{cs}^0$ pentaquark exchange.
• Figure 5: Total cross section for the $K^- p \to \phi \Lambda$ reaction as a function of $P_{\rm Lab}$. The green dotted and blue dashed curves denote the contributions from $K$- and $K^*$-Reggeon exchanges, respectively, while the black solid curve represents their sum. Experimental data are taken from Ref. Lindsey:1966zz (triangles) and Ayres:1974aj (squares).