Investigating nucleon resonances in the $pp\to K^+K^+ΛΛ$ reaction

Abstract

In this work, we investigate the \(pp \to K^+ K^+ ΛΛ\) reaction using an effective Lagrangian approach and the isobar model. The calculation includes the exchange of \(π\), \(η\), \(σ\), \(ρ\), \(ω\), and \(K\) mesons, as well as contributions from eight nucleon resonances: \(N(1535)\), \(N(1650)\), \(N(1710)\), \(N(1720)\), \(N(1895)\), \(N(1900)\), \(N(2060)\) and \(N(2120)\). The double-resonance excitation mechanism (\(NN \to N^* N^*\)) is found to dominate this reaction over the entire energy range considered. Among the exchanged mesons, the \(η\) exchange provides the largest contribution at lower energies, whereas the \(K\) exchange dominates at higher energies. Near the threshold, \(N(1535)\) and \(N(1650)\) play the most important roles, while at higher energies \(N(1710)\) and \(N(1720)\) become dominant. Due to isospin conservation, this reaction is predominantly coupled to nucleon resonances, providing a relatively clean channel for \(N^*\) spectroscopy. Our results indicate the unique potential of this reaction for studying nucleon resonances and provide a theoretical reference for future experimental studies at HIAF.