Nucleon resonances in the $\pi^- p \to K^0 \Lambda$ reaction near threshold

Abstract

We investigate the two-body reaction $\pi^- p \to K^{0} \Lambda$ within the effective Lagrangian approach and the isobar model. In addition to the "background" contributions from $t$-channel $K^*$ exchange, $u$-channel $\Sigma(1192)$ and $\Sigma^*(1385)$ exchanges, and $s$-channel nucleon pole terms, the contributions from the nucleon resonances $N^*(1535)$, $N^*(1650)$, and $N^*(1720)$ are investigated. It is shown that the inclusion of these nucleon resonances contributions leads to a good description of the experimental total and differential cross sections data at low energy region. The $s$-channel $N^*(1535)$, $N^*(1650)$, and $N^*(1720)$ resonances and the $t$-channel $K^*$ exchange give the dominant contributions below $W = 1.76$ GeV, while the $u$-channel $\Sigma(1192)$ and $\Sigma^*(1385)$ exchanges give the minor contributions.