Nucleon Motion Effects for Hyperon Production Reactions

Single-particle potentials of hyperon, e.g. $\Lambda,~\Sigma,~\Xi$, in nuclei are determined from analysis of $^{32}$Si$(\pi^{\pm},K^+)$ at 1.2 GeV/c and $^{12}$C$(K^-,K^+)$ at 1.65 GeV/c. We use the semiclassical distorted wave (SCDW) model to accurately describe these reactions. As an important advantage of the use of the SCDW model, the Fermi motion of a struck nucleon in the target nucleus is explicitly taken into account. Consequently, the $\Sigma$-$^{32}$Si potential derived from $^{32}$Si$(\pi^-,K^+)$ with the SCDW model is significantly different from a result of previous analysis, where a rather simple reaction-model was adopted. In the present paper we discuss effects of the Fermi motion of a struck target-nucleon on the energy spectrum of the outgoing particle in detail and aim to clarify the reaction mechanisms of the inclusive $(\pi^{\pm},K^+)$ and $(K^-,K^+)$ reactions. We will also discuss the role of multistep processes, which can easily be included in the SCDW model analysis, in the study of the hyperon single-particle potential.