Collective Flow of Λ Hyperons within Covariant Kaon Dynamics

The collective flow of Λ hyperons produced in association with positively charged kaon mesons in nuclear reactions at SIS energies is studied using the quantum molecular dynamics (QMD) model within covariant kaon dynamics. Our calculation indicates that both the directed and differential directed flows of Λs are almost in agreement with the experimental data. This suggest that the covariant kaon dynamics based on the chiral mean field approximation can not only explain the collective flow of kaon mesons, but also give reasonable results for the collective flow of Λ hyperons at SIS energies. The final−state interaction of Λ hyperons with dense nuclear matter enhances their directed flow and improves the agreement of their differential directed flow with the experimental data. The influence of the interaction on the Λ collective flow is more appreciable at large rapidity or transverse momentum region.