The Theoretical Study of $\pi^+p\to pa_0^+\phi$ Reaction

We study the production of hyperon resonances in the $\pi^+p\to pa_0^+\phi$ reaction within an effective Lagrangian approach. The model includes the production of $\Delta(1940)$ and $\Delta(1920)$ in the intermediate state excited by the $\rho$ and $p$ exchanges between the initial proton and $\pi$ meson. Due to the large contribution of $\rho$ exchange in $\Delta(1940)$ production, $\Delta(1940)$ is found a significant contribution near the threshold in this reaction. We provide total and differential cross section predictions for the reation and discuss the possible influence of model parameters, off-shell effects and branching ratios for $\Delta(1940)\to pa_0$ and $\Delta(1920)\to pa_0$ decays, which will be useful in future experimental studies. This reaction can provide a platform for studying the features of $\Delta(1940)$ resonance, especially the coupling to $pa_0$ channel.