Study of \(\Lambda \) Identification Method by the \(\pi ^{ - }p \to K^{0}\Lambda \) Reaction for a \(\Lambda p\) Scattering Experiment at J-PARC

The \(\pi ^{ - }p \to K^{0}\Lambda \) reaction is an important elementary process to produce \(\Lambda \) from a proton target and is a key for a \(\Lambda p\) scattering experiment where the momentum of \(\Lambda \) should be tagged from the missing momentum of the \((\pi ^{ - },K^{0})\) reaction. However, the \((\pi ^{ - },K^{0})\) spectroscopy method has not been established yet due to the difficulty of the K^0 detection. Therefore, we have proposed a new K^0 detection method where \(\pi ^{ + }\) and \(i^{ - }\) from the K^0 decay are measured by a forward magnetic spectrometer and a detector cluster surrounding the target, respectively. The feasibility of the K^0 detection method was confirmed by analyzing the J-PARC E40 data taken with such a detector system. In the analysis, \(\Lambda \)’s were successfully identified in the missing mass spectrum of the \(\pi ^{ - }p \to K^{0}X\) reaction.