Study of Hyperon-Nucleon Interaction in the ReactionK−d→π−pΛat Rest

A $\Lambda p$ system with high statistics and mass resolution was studied in detail. The broad bump in the low-mass region can be attributed to contribution from both the impulse and final-state-interaction mechanisms. The low-energy $\Lambda p$ scattering parameters are deduced to be $a_0=-2.0\mathrm{}\pm 0.5$ and ${\mathcal{r}}_0=3.0\mathrm{}\pm 1.0$ F. The higher mass spectrum can be fitted to two Breit-Wigner resonant structures with $M_1=2128.7\mathrm{}\pm 0.2$, ${\Gamma }_1=7.0\mathrm{}\pm 0.6$, and $M_2=2138.8\mathrm{}\pm 0.7$, ${\Gamma }_2=9.1\mathrm{}\pm 2.4$ MeV. Attempts were carried out to understand these peaks via a $\Sigma N$ final-state-interaction model.