Analysis of the reaction

In this work, we study the reaction in an effective Lagrangian approach and isobar model. Compared to previous studies using a Regge-plus-resonance model, we consider the contributions of the t-channel (K and ) and u-channel (proton) exchanges explicitly as the background contribution. To restore the gauge invariance of the amplitude violated by introducing the phenomenological form factors, we employ two different methods from the literature. Then, we discuss the roles of possible resonance contributions in this reaction and present predictions of Λ polarization based on various models. We find that the contribution of the background terms plays an important role in the present reaction. Meanwhile, the , , and resonances may also contribute to this reaction. Due to the uncertainties of the present data and relatively small contributions of the hyperon resonances, we cannot identify the roles of various hyperon resonances in the present work. However, we show that the measurement of the spin polarization of the final Λ will be helpful to verify various models.